mate of the cost or advantage of every transit which is made of person or property. The second, is that of free intercourse in adverse or inclement seasons of the year, when all other means of conveyance are embarrassed or interrupted. We will add on this subject the testimony of one of the most cautious and experienced engineers in Great Britain, whose opportunities of forming correct opinions on this subject have not been surpassed by those of any other individual.

"The question that railways are fitted for the conveyance of general merchandize, has been decided in the most conclusive and practical manner. Being applicable at greater rates of speed than by any other mode, not only for the conveyance of passengers, but also for general merchandize, has affixed a value to railroads possessed by no other means of conveyance. Uniting the several qualities of being alike adapted for the transit of light and heavy goods, and the conveyance of passengers, will unques

nage or passengers be 5,000 in each district, it passed an act giving corporate powers for the
will, at one dollar per ton or passenger for this construction of the railway or its branches in
distance, amount to 5,000 dollars. If we now the county of Berkshire; and by connecting
take the aggregate of the ten railroads in the with the Harlæm Railroad, provision is already
several districts, estimated by the same rule, made for its extension into the heart of our
the aggregate compensation or income for the great commercial city.
100 miles of railroad will amount to $50,000.
This is a fair exhibition of the operation of rail-
ways in single isolated districts, each leading to
its separate local market.

We will now examine the effect of a continuous railway through the same number of districts of like dimensions, and furnishing a like amount of tonnage or passengers, the entire length of railway being the same as before, bat leading to a common market at the termination of the tier of districts, as at A. in the following diagram :

It is here evident, that the tonnage or passennumber of miles in the district as in the former

RAILROAD.-Extract from the log-book of a gentleman who left New-York on Thursday last for Baltimore. Left New-York at 6. 10, arrived at Amboy at 8. 21. Left Amboy at 8. 31, and arrived at Bordentown at 12. 8. Left at 12. 11, and arrived at Philadelphia at 2. 36. Left Philadelphia at 3. 16, arrived at New Castle at 6. 15. Left at 6. 21, and arrived at Frenchtown 7. 21. Left at 7. 53, and arrived at Baltimore at 12. 35. A considerable time lost in changing horses between Amboy and Bordentown. The distance from New Castle to Frenchtown, 16 miles, which was performed the route for the steam to go off pish, pish, at in one hour, besides having made two stops on

tionably lead to the substitution of railways for gers of each district will pass the same average the cows, which were on the road. In one inother modes, not possessing such properties, case, but mark the difference which follows. stance the boy who drove the cows was more in all cases where the extent of traffic is such The tonnage of the district nearest to the mar.frightened than the cattle he ran one way and the cattle the other.-[Com. Adv.]

as to justify the out-lay of capital necessary ket at A. will reach its destination in travelling
for their construction."-(Wood on Railroads,
2d edition, 1831.)

There remains in concluding our inquiries, but one point to be examined. Is not the construction of a long line of railroad, through a

an average of five miles from the common cen-
cond district, after travelling the same distance,
tre of the district; but the products of the se-
district, or an average distance of 15 miles, and
must pass through the entire length of the first

[From the Frederick (Md.) Examiner, of 26th June.] Esq. President of the Railroad Company, and RAILROAD AND CANAL.-Philip E. Thomas, John Eaton, Esq. President of the Canal Com

agricultural or manufacturing country, an un- the tonnage of the third district must pass in pany, accompanied by a committee of the Di.

certain or hazardous enterprize?
It is often said that those railroads only can

Rocks, on Wednesday last, for the purpose of rectors of each Company, visited the Point of

its turn 25 miles: and the same ratio of inbe profitable which are of moderate extent, and//crease will apply to all the remaining districts, instituting measures to carry into effect the which unite great cities or thoroughfares, and producing the following results: the case of the Liverpool and Manchester Rail

15 do......

2d do

do. do.

3d do.

do.

do.

25 do.

4th do.

do.

do.

35 do.

cost of trans- compromise for the passage of both works
round the Point of Rocks. We have heard that
portation.
.$5,000 the best disposition to accommodate all differ-
15,000 ences upon the subject was evinced, and that
.25,000 the two works will probably now progress in
.35,000
harmonious co-operation.
45,000
..55,000
.65,000
Rafts and Canal Navigation.-The great quantity
.75,000 of timber which is brought into the Erie canal, in
.85,000 rafts, by the opening of the Oswego and Cayuga and
95,000 Seneca canals, has produced so much detention at
the locks, during the press of business for several
weeks since the opening of navigation, as to call for
some effort to relieve this inconvenience hereafter,
either by the construction of double locks, or such
regulations as will induce the lumbermen to trans-
port their rafts during the summer months, interme.
diate between the press of business on the canal in
the spring and fall.

road is often referred to as a case in point. From 1st dis. to market at A. estimated 5 miles,
This idea or objection is by no means new. It
was urged with great confidence against the
construction of the Erie Canal, and ruin was
confidently predicted to the finances of the state,
should the legislature embark its interests in
that mad adventure. The example of this ca-
nal may be referred to with more safety than
that of the Liverpool Railway, and it proves
that the true principles on which the success of
$500,000
these works depend have been mistaken by Thus it appears that the amount of income
the objectors, and that, other things being or compensation derived from the same amount
equal, the success or profit of a line of canal or of tonnage or passengers, from the same num-
railway depends very much upon its extension, ber of districts, on a continuous railway of the
and that the value increases with the length in same aggregate extent, but leading through
a geometric ratio. This matter is generally the several districts in succession to a common
understood by our civil engineers, and it is ad-market, will amount to $500,000, being ten
mitted that in penetrating a secluded country, times the amount which the same business will
although the distant portions of the work may, afford on ten local railways of ten miles each,
if separately considered, fail to remunerate for whde from the more simple economy in the
their construction, yet the increased mileage of superintendance and management of the longer
the remote trade on the more frequented por-route, the aggregate expenses would be but
tions of the work will more than compensate little increased.
for the deficiency.

The attention of the public officers who have charge of the canals has been called to this subject, that the Canal Board, at an informal meeting on the and we are authorized by the Comptroller to say, 17th inst., took into consideration the transportation of timber in rafts on the Erie and Champlain canals, and the present rates of toll on lumber transported in that manner; and that such of the members of the board, as were present, entertain the opinion that some new regulations on this subject will the next year become indispensable. They are not now prepared to say what particular measure will be adop ted; but it is not improbable that on timber transpor. ted in rafts during the spring and fall, when the canal is thronged with boats, the owners of rafts will be and to increase the number of hands, so that each required to diminish the number of cribs in a ton, crib shall be in the immediate custody of some per

We find, therefore, that extended lines of The importance of this view of the subject, communication, leading from great markets toand its bearing upon the interests of the pro-wards the interior, are by far the most profitaposed railway, which is to lead from the city of ble, especially in a country of such wide extent New-York towards the interior of our country as our own, and it is only the converse of the in another direction,* induces a more specific objection that holds true, viz.: That short lines examination of the question under review. of railway or canal cannot be made profitable In order to give a correct illustration, we will in this country, unless in uniting important suppose ten separate districts of country of cities or great lines of communication. equal dimensions, and furnishing an equal It is these obvious considerations which have son, and so managed as not unnecessarily to impede amount of tonuage or passengers, each district given such value to the Erie Canal. Had this the navigation of boats; in addition to this the tolls to be intersected through its geographical cen- great work been restricted to one-fourth of its on rafts navigating the canals in the spring and fall tre by a railway leading to a market on one of present length, in its extension from the Hud- may be increased. In order to relieve the rafts from the its borders, at the point a, as marked on the son, it would probably have remained an an-effects of these restrictions, and to present the strongannexed diagram: nual burden upon the finances of the state, in- est inducements for their transportation during that stead of imparting, as it now does, happiness, part of the season when the canal is not crowded wealth, enterprize, and confidence, throughout with boats, it is proposed to reduce the tolls on all our widely extended and prosperous commu- rafts transported during three months in the middle nity.

The time will soon arrive when the subscriptions for the stock of the New-York and Albany Railroad will be open to the public. After the company shall have been organized, the the final location and execution of the work will surveys and other necessary arrangements for protract the time at which the directors will mer states that a silk filature is about to be escommence calling in the instalments for one or tablished in Baltimore, and that Mr. Hitchcock, two years longer, and we may then expect to proprietor of that paper, is authorised to pursee the work in active progress. The Legisla-chase cocoons at twenty-five to fifty cents per ture of Massachusetts during its last session pound, according to their quality.

A few Remarks on the Relation which subsists || Were the linear dimensions increased ten production of such massy webs, they choose
between a Machine and its Model. By ED-times, the superfices would be enlarged one the most secluded spots; while the smaller
WARD SANG, Teacher of Mathematics, hundred, and the solidity one thousand times. species, dreading no inconvenience from a
Edinburgh.
On these facts, the most important which geo- frequent renewal of theirs, stretch them from
At first sight, a well constructed, model metry presents, my after-remarks are most-branch to branch, and often from tree to tree.
presents a perfect representation of the dis-ly to be founded.
I have often been astonished at the prodi.
position and proportion of the parts of a ma- All machines consist of moveable parts, gious lengths of these filaments, and have
chine, and of their mode of action.
sliding or turning on others, which are bound mused on the immense improvement which
Misled by the alluring appearance, one is together by bands, or supported by props. must take place in science, and in strength of
apt, without entering minutely into the in-To the frame work I shall first direct my at-materials too, ere we could, individually,under-
quiry, also to suppose that the performance tention.
take works of such comparative magnitude.
of a model is, in all cases, commensurate In the case of a simple prop, destined to When a beam gives support laterally, its
with that of the machine which it is formed to sustain the mere weight of some part of the strength is proportioned to its breadth, and to
represent. Ignorant of the inaccuracy of machine, the strength is estimated at so the square of its depth conjointly. If, then,
such an idea, too many of our ablest mecha- many hundred weights per square inch of such a beam were enlarged ten times in each
nicians and best workmen waste their time cross section. Suppose that, in the model, of its linear dimensions, its ability to sustain a
and abilities on contrivances, which, though the strength of the prop is sufficient for dou-weight placed at its extremity would, on ac-
they perform well on the small scale, must, ble the load put on it, and let us examine the count of the increased distance from the point
from their very nature, fail when enlarged. effect of an enlargement, ten-fold, of the of insertion, be only one hundred times aug-
Were such people acquainted with the mode scale according to which the instrument is mented, but the load to be put upon it would
of computing the effects, or had they a know-constructed. By such an enlargement, the be one thousand times greater; and thus, al-
ledge of natural philosophy, sufficient to ena- strength of the prop would be augmented though the parts of the model be quite strong
ble them to understand the basis on which 100 times; it would be able to bear 200 enough, we cannot thence conclude that
such calculations are founded, we should see loads such as that of the model, but then the those of the enlarged machine will be so.
fewer crude and impracticable schemes pre-weight to be put on it would be 1000 times It may thus be stated as a general princi-
maturely thrust upon the attention of the pub- that of the small machine, so that the prop in ple, that, in similar machines, the strengths
lic. This knowledge, however, they are too the large machine would be able to bear only of the parts vary as the square, while the
apt to regard as unimportant, or as difficult of the fifth part of the load to be put on it. weights laid on them vary as the cube of the
attainment. They are startled by the absurd The machine, then, would fall to pieces by corresponding linear dimension.
distinction which has been drawn between its own weight.
This fact cannot be too firmly fixed in the
theory and practice, as if theory were other Here we have one example of the errone-minds of machine makers; it ought to be taken
than a digest of the results of experience; ous manner in which a model represents the into consideration ever on the smallest
or, if they overcome this prejudice, and re- performance of a large instrument. The change of scale, as it will always conduce
solve to dive into the arcana of philosophy, supports of small objects ought clearly to be either to the sufficiency or to the economy
they are bewildered among names and signs, smaller in proportion than the supports of of a structure. To enlarge or diminish the
having begun the subject at the wrong end. large ones. Architects, to be sure, are ac-parts of a machine all in the same propor-
That the attainment of such knowledge is customed to enlarge and to reduce in proportion, is to commit a deliberate blunder. Let
attended with difficulty is certain, but it is tion; but nature, whose structures possess us compare the wing of an insect with
with such difficulty only as can be overcome infinitely more symmetry, beauty, and varie- that of a bird: enlarge a midge till its whole
by properly directed application. It would ty, than those of which art can boast, is con-weight be equal to that of the sea-eagle, and,
be, indeed, preparing disappointment to buoy tent to change her proportions at each change great as that enlargement must be, its wing
them up with the idea, that knowledge, of size. Let us conceive an animal having will scarcely have attained the thickness of
even of the most trivial importance, can be the proportions of an elephant and only the writing paper; the falcon would feel rather
acquired without labor. Yet it may not be size of a mouse; not only would the limbs of awkward with wings of such tenuity. The
altogether unuseful, for the sake both of those such an animal be too strong for it, they wings of a bird, even when idle, form a con-
who are already, and of those who are not, would also be so unwieldy that it would have spicuous part of the whole animal; but there
acquainted with these principles, to point out no chance among the more nimble and better are insects which unfold, from beneath two
the more prominent causes, on account of proportioned creatures of that size. Reverse scarcely perceived covers, wings many times
which the performance of no model can, on the process, and enlarge the mouse to the more extensive than the whole surface of
any occasion, be considered as representa- size of an elephant, and its limbs, totally una-||their bodies.

resorted to, as

tive of that of the machine. Such a notice ble to sustain the weight of its immense body, The larger animals are never supported
will have the effect of directing the attention, would scarcely have strength to disturb its laterally; their limbs are always in a posi-
at least, to this important subject. In the position even when recumbent.
tion nearly vertical: as we descend in the
present state of the arts, the expense of con- The very same remarks apply to that case scale of size the lateral support becomes
structing a full-sized instrument is, in almost in which the weight, instead of compressing, more frequent, till we find whole tribes of
every instance, beyond what its projector distends the support. The chains of Trinity insects resting on limbs laid almost horizon-
would feel inclined, or even be able, to incur. Pier are computed to be able to bear nine tally. The slightest consideration will con-
The formation of a model is thus universally times the load put on them. But if a similar vince any one that lateral or horizontal limbs
a prelude to the attempt on structure were formed of ten times the linear would be quite inadequate to support the
the large scale. An inquiry, then, into the dimensions, the strength of the new chain weight of the larger animals. Conceive a
relation which a model bears to the perfect would be one hundred times the strength of spider to increase till his body weighed as
instrument, can hardly fail to carry along with that at Trinity, while the load put upon it much as that of a man, and then fancy one
it the advantage of forming a tolerable guide, would be one thousand times greater; so that of us exhibiting feats of dexterity with such
in estimating the real benefit which a contri- the new structure would possess only nine- locomotive instruments as the spider would
vance is likely to confer upon society. tenths of the strength necessary to support then possess!
In the following paper I propose to exitself. Of how little importance, then, in The objects which I have hitherto com-
amine the effect of a change of scale on the bridge building, whether a model construct-pared have been remote, that the comparisons
strength and on the friction of machines, and, ed on a scale of perhaps one to a hundred might be the more striking; but the same
at the same time, to point out that adherence support its own weight! Yet, on such principles may be exhibited by the contrast
to the strictest principles which is apparent in grounds, a proposition for throwing a bridge of species the most nearly allied, or of indi-
all the works of nature, and of which I mean of two arches across the Forth, at Queens-viduals even of the same species. The lar-
to avail myself in fortifying my argument. ferry, was founded. Putting out of view the ger species of spiders, for instance, rarely
Previous, however, to entering on the sub-road-way and passengers altogether, the have their legs so much extended as the
ject-proper, it must be remarked that, when weight of the chain alone would have torn it smaller ones; or, to take an example from
we enlarge the scale according to which any to pieces. The larger species of spiders the larger animals, the form of the Shetland
instrument is constructed, its surface and its spin threads much thicker, in comparison poney is very different from that of the Lon-
bulk are enlarged in much higher ratios. If, with the thickness of their own bodies, than don dray horse.

for example, the linear dimensions of an in- those spun by the smaller ones. And, as if How interesting it is to compare the diffe-
strument be all doubled, its surface will be sensible that the whole energies of their sys-rent animals, and to trace the gradual change
increased four, and its solidity eight-fold.tems would be expended in the frequent re-"of form which accompanies each increase of

size! In the smaller animals, the strength||which will produce an equable communica-||sure; this is a slight inaccuracy of concep is, as it were, redundant, and there is room tion of motion with the least possible fric- tion, for the actual resistance is not at all infor the display of the most elaborate orna- tion. For the equable communication of creased by increasing the relative velocity; ment. How complex or how beautiful are motion, two methods have been recommend- but the effect of that resistance, in retarding the myriads of insects which float in the air, ed; one, that the lower part of the face of the motion of the wheels, may be shown, or which cluster on the foliage! Gradually each tooth should be a straight line in the from the general laws of mechanics, to be the larger of these become more simple in direction of the radius, and the upper, a por- proportional to the relative velocity thus astheir structure, their ornaments less profuse. tion of an epicycloid; that is, of a curve certained. The structure of the birds is simpler and described by a point of a circle rolling on When it is possible to make one wheel act more uniform, that of the quadrupeds still the wheel, of which the diameter must be on teeth fixed in the concave surface of anomore so. As we approach the larger quad-half that of the opposite wheel; and in this ther, the friction may be thus diminished in rupeds, ornament, and then elegance, disap-case it is demonstrable, that the plane sur- the proportion of the difference of the diapear. This is the law in the works of na-face of each tooth will act on the curved meters to their sum. ture, and this ought to be the law among the surface of the opposite tooth, so as to proworks of art.

duce an equable angular motion in both TO ASCERTAIN THE HEIGHT OF A STEEPLE, Among one class of animals, indeed, it wheels: the other method is, to form all the TOWER, &c.-Take two sticks of any but may be said that this law is reversed. We surfaces into portions of the involutes of cir-equal length, and holding one perpendicular, have by no means a general classification of cles, or the curves described by the point of place one end of the other against its centre, the fishes; but, among those with which we a thread which has been wound round the so as to form a right angle with it; having are acquainted, we do not perceive such a wheel while it is uncoiled; and this method done this, place your eye at the other end, prodigious change of form. Here, however, appears to answer the purpose, in an easier and advance towards, or recede from, the the animal has not to support its own weight; and simpler manner than the former. The object the height of which you wish to asand whatever increase may take place in the following figure represents the teeth, &c. of certain, until the upper and lower ends of the size of the animal, a like increase takes place two wheels, formed into involutes of circles, perpendicular stick shall appear to touch its in the buoyancy of the fluid in which it described by uncoiling a thread from the top and bottom at the same time; then, from swims. Many of the smaller aquatic ani-dotted circles; the point of contact of the the spot on which you stand, measure the mals exhibit the utmost simplicity of struc- teeth being always in the straight line, which distance to the foot of the object, and this ture; but we know too little of the nature of touches both circles. will be its exact height.

their functions to draw any useful conclusions

from this fact.

OF WHEEL WORK.-In treating of the simple mechanical power, called the wheel and axle, (see The Artisan, vol. i. p. 86), we stated that motion was communicated from one wheel to another, either by belts and straps passing over them, or by teeth cut in the circumference of each, and working in one another. We shall now eater a little more fully into the subject and endeavor to explain some of the most useful principles upon which this branch of practical mechanics depends, and also to point out the various methods of applying this mechanical power in the motion of different kinds of machinery.

Architecture.-Of the Orders of Architecture.

The moderns have applied the term order to those architectural forms with which the Greeks composed the façades of their temples.

The principal members of an order are, 1st, a platform; 2d, perpendicular supports; and 3d, a lintelling or covering connecting the tops of these supports, and crowning the edifice.

The proportioning of these parts to the edifice and to each other, and at the same time adapting characteristical decorations, constitutes an order, canon, or rule.

The principal member of an order is the Where a broad strap runs on a wheel, it perpendicular support or column. The acis usually confined to its situation, not by It may be experimentally demonstrated, companiments being subservient to this leadcausing the margin of the wheel to project, that an equable motion is produced by the ac- ing feature, the bottom of the column is but, on the contrary, by making the middle tion of these curves on each other; if we fixed either on a general artificial platform, prominent, as represented by the following cut two boards into forms, terminated by or each upon a particular plinth, or both. wheel or pulley, on which a broad strap runs, them, divide the surfaces by lines into equal The lower part of the column, which rests the surface being convex; the wheel which or proportional angular portions, and fix them upon the square plinth, is sometimes encomdrives it is of a similar form but, its upper on any two centres, we shall find that, as they passed with mouldings, which, in allusion to part only is shown in the figure. revolve, whatever parts of the surfaces may their position, are, in conjunction with the be in contact, the corresponding lines will plinth, called the base. always meet each other. The top part of the column is also covered Both of these methods may be derived with a square plinth, with its sides straight from the general principle, that the teeth of or curved, and generally accompanied by cirthe one wheel must be of such a form, that cular mouldings or sculptured decorations their outline may be described by the revo- upon the top part of the column, which is The reason of the middle being made pro-lution of a curve upon a given circle, while immediately underneath it; this, taken tominent may be understood by examining the outline of the teeth of the other wheel gether, is called the capital. The body of the manner in which a tight strap, running is described by the same curve revolving the column, which reaches between the base on a cone, would tend to run towards its within the circle. It has been supposed and capital, is termed the shaft: it is the thickest part. Sometimes also pins are fixed by some of the best officers, that the epicy- frustrum of a cone, with sometimes a plain in the wheels, and admitted into perforations cloidal tooth has also the advantage of com-surface, but frequently having perpendicuin the straps; a mode only practicable where pletely avoiding friction; this is, however, lar flutings, either meeting in an edge or the motion is slow and steady. A smooth by no means true, and it is even impractica- leaving a small plane space between them. motion may also be obtained, with consider- ble to invent any form for the teeth of a The lintelling or covering, which lies upon able force, by forming the surfaces of the wheel which will enable them to act on and connects the column, is termed the Enwheels into brushes of hair. More com- other teeth without friction. In order to di- tablature, and is sub-divided into three parts, monly, however, the circumferences of the minish it as much as possible, the teeth must named architrave, frieze, and cornice: the contiguous wheels are formed into teeth, im- be as small and as numerous as is consistent architrave consists of a mere lintel laid pelling each other, as with the extremities with strength and durability; for the effect along the tops of the columns; the frieze of so many levers, either exactly or nearly of friction always increases with the dis- represents the ends of the cross beams restin the common direction of the circumfe-tance of the point of contact from the line ing upon the former, and having the spaces rences; and sometimes an endless screw is joining the centres of the wheels. In calcu- between filled up, having mouldings also lating the quantity of the friction, the velo- fixed to conceal the horizontal joint, and di

substituted for one of the wheels.

In forming the teeth of wheels, it is of city with which the parts slide over each vide it from the architrave; and the upper consequence to determine the curvature other has generally been taken for its mea-member or cornice represents the project

ing eaves of a Greek roof, showing the ends
of the rafters.
These definitions will be easily understood
by an inspection of the following figure:

D

below the top, and an inch under the surface||pneumatic apparatus, and is extremely use. of the water. In one part of this shelf there ful in all experiments in which gasses are is a slit, into which the extremity of the iron concerned. Into the glass vessel E put a tube plunges. The heat of the fire expels quantity of black oxide of manganese in the greatest part of the air contained in the powder, and pour over it as much of that bottle. It may be perceived bubbling up liquid which in commerce is called oil of through the water of the vessel C from the vitriol, and in chemistry sulphuric acid, as extremity of the iron tube. At first the air is sufficient to form the whole into a thin bubbles come over in torrents; but after paste; then insert into the mouth of the veshaving continued for some time, they cease sel the glass tube F, so closely that no air altogether. can escape except through the tube. This Meanwhile the bottle is becoming gradu-may be done either by grinding, or by cover. ally hotter. When it is obscurely red the ing the joining with a little glazier's putty, air bubbles make their appearance again, and then laying over it slips of bladder or and become more abundant as the heat in-linen dipped in glue, or in a mixture of the creases. This is the signal for placing the white of eggs and quick-lime. The whole glass jar D, open at the lower extremity, pre- must be made fast with cord. viously filled with water, so as to be exactly The end of the tube F is then to be over the open end of the gun-barrel. The air plunged into the pneumatic apparatus D, bubbles ascend to the top of the glass jar D, and the jar G, previously filled with water, to and gradually displace all the water. The be placed over it on the shelf. The whole glass jar D then appears to be empty, but is apparatus being fixed in that situation, the in fact filled with air. It may be removed glass vessel E is to be heated by means of in the following manner: Slide it away aa lamp or candle. A quantity of oxygen little from the gun-barrel, and then dipping gas rushes along the tube F, and fills the jar A, the capital-B, shaft-C, architrave any flat dish into the water below it, raise it G. As soon as the jar is filled, it may be D, frieze-E, cornice.

F

B

PEDESTAL.

A

B

C

A, the cornice-B, the base-C, the

History of Chemistry.

on the dish and bear it away. The dish slid to another part of the shelf, and other must be allowed to retain a quantity of water jars substituted in its place, till as much gas in it, to prevent the air from escaping. Ano- has been obtained as is wanted. The last ther jar may then be filled with air in the of these methods of obtaining oxygen gas same manner; and this process may be con- was discovered by Scheele, the first by Dr. tinued either till the manganese ceases to Priestley. give out air, or till as many jars-full have The gas obtained by the above processes been obtained as are required.* This meth- was discovered by Dr. Priestley on the 1st od of obtaining and confining air was first of August, 1774, and called by him dephloinvented by Dr. Mayou, and afterwards much gisticated air. Mr. Scheele, of Sweden, improved by Dr. Hales. All the air obtained discovered it before 1777, without any pre. by this or any other process, or, to speak vious knowledge of what Dr. Priestley had more properly, all the airs differing in their properties from the air of the atmosphere, have, in order to distinguish them from it, plinth.afterwards employ-t been called gasses; and this name we shall

OF OXYGEN GAS.-Oxygen gas may be obtained by the following process:

B

Α.

C

Oxygen gas may also be obtained in a dif. ferent manner, thus: Let D represent a G

done: he gave it the name of empyreal air.* Condorcet gave it first the name of vital air; and Mr. Lavoisier afterwards called it oxygen gas: a name which is now generally received, and which we shall adopt.

1. Oxygen gas is colorless, and invisible like common air. Like it, too, it is elastic, and capable of indefinite expansion and compression.

2. If a lighted taper be let down into a phial filled with oxygen gas, it burns with such splendor that the eye can scarcely bear the glare of light, and at the same time produces a much greater heat than when burn. ing in common air. It is well known that a candle put into a well closed jar, filled with common air, is extinguished in a few se conds. This is also the case with a candle in oxygen gas; but it burns much longer in an equal quantity of that gas than of common air.

wooden trough, the inside of which is lined Procure an iron bottle of the shape A, with lead or tinned copper; and let C be a and capable of holding rather more than an cavity in the trough, which ought to be a foot * This process, by which the joinings of vessels are English pint. To the mouth of this bottle deep. The trough is to be filled with water for that purpose are called lutes. The lute most commonly made air tight, is called luting, and the substances used an iron tube bent like B is to be fitted by at least an inch above the shelf A B, which used by chemists, when the vessels are exposed to heat, is. grinding. A gun-barrel deprived of its buit runs along the inside of it, about three inch-fat lute, made by beating together, in a mortar, fine clay and end answers the purpose very well. boiled linseed oil. Bees-wax, melted with about one eighth Into es from the top. In the body of the trough, part of turpentine, answers very well, when the vessels the bottle put any quantity of the black ox- which may be called the cistern, the jars des- are not exposed to heat. The accuracy of chemical expeide of manganese* in powder; fix the iron tined to hold gas are to be filled with water, ing the joinings properly with futing. The operation is alriments depends almost entirely in many cases upon secur tube into its mouth, and the joining must be and then to be lifted, and placed inverted ways tedious and some practice is necessary before one air tight; then put the bottle into a common upon the shelf at B. can succeed in Inting accurately. Some very good direcfire, and surround it on all sides with burntions are given by Lavoisier. See his Elements, Part ni. chap. 7. In many cases luting may be avoided altogether, ing coals. The extremity of the tube must by using glass vessels properly fitted to each other by grindbe plunged under the surface of the water ing them with emery. with which the vessel C is filled.

This trough, which was invented by Dr. Priestley, has been called by the French chemists the pneumato-chemical, or simply * For a more exact description of this and similar appa- SINKING WELLS.--Bishop Heber mentionChemistry, and Priestley on Airs; and above all, to Mr. of Asia. ratus, the reader is referred to Lavoisier's Elements of a curious way of sinking wells in some parts Watt's description of a pneumatic apparatus, in Beddoe's When the ground is sandy, a cys Considerations on Factitious Airs. lindrical tower of brick or stone work i. This substance shall be afterwards described. It is The word gas was first introduced into Chemistry by made of the intended size of the well. This now very well known in Britain, as it is in common use Van Helmont. He seems to have intended to denote by is suffered to remain until the masonry bes with bleachers, and several other manufacturers, from it every thing which is driven off from bodies in a state of comes indurated, and then it is gradually unwhom it may be easily procured. vapors by heat.

This vessel may be of wood or japanned tin plate. It has a wooden shelf running along two of its sides, about three inches

dermined until it is sunk even with the sur- liarly adapted to sawing regular and eccen-||communication will be had with the Susqueface of the ground. If the well is not suf-tric circles, such as felloes for wheels, chair hanna, also at the junction of the Lackawana, ficiently deep, they add more masonry, and tops, seats, legs, and backs, and circular and I know the ground is favorable; and by thus again undermine. blocks for brushes; and it saws chair tops reaching the Upper Delaware and the Upper and seats with great accuracy on a bevel. Susquehanna, so many sources of business FIRE PROOF CEMENT.-The French ce- Each segment of a wheel is cut its proper are opened that it would be worth while to ment for the roofs of houses, to preserve length and proper inclination for the joint make it, if it went no further. But now every the wood and protect it from fire, is made in the holes are bored for the dowels and section will add business, and when the route the following manner : spokes, and the hubs are bored on a prin- reaches the head of Alleghany river, the Take as much lime as is usual in making ciple entirely new, making every spoke stand a pot full of whitewash, and let it be mixed with the greatest exactness from the centre Blanchard steamboats will run from Hamilton in a pail full of water; in this put two and to the extreme of the circle. The machine to Pittsburg, and at low water to Cincinnati ; a half pounds of brown sugar, and three is perfectly simple in its construction, not and the continuation of the road to the Lake pounds of fine salt; mix them well together, liable to get out of repair, and easy to man-opens the trade of the coast of all these inland and the cement is completed. A little lamp-age and understand. A few hours' acquaint- seas.

of two-horse power.

A part of the principle of the same machine is applied to a small portable frame, and used for sawing wood for the fire with astonishing rapidity.[Courier & Enq.]

black, yellow ochre, or other coloring com-ance with it will enable any one, whether The article alluded to speaking of the duramodity, may be introduced to change the co-mechanic or otherwise, to operate on it as bility of cheap railroads, I give this explanation lor of the cement, to please the fancy of those well as the inventor. It is only six feet of my ideas of the means in 1829, and have who use it. It has been used with great square, and is propelled by a steam engine since made some improvement thereon, though success, and been recommended particularpreferring durable works where they can be ly as a protection against fire. Small sparks afforded. J. L. S. of fire, that frequently lodge on the roofs of houses, are prevented by this cement from "Specification of an improvement or combiburning the shingles. So cheap and valuanation in the art of constructing Railroads, ble a precaution against the destructive elewhereby timber employed therein may be inment ought not to pass untried. Those who creased in durability, viz.: wish to be better satisfied of its utility can easily make the experiment, by using on a small temporary building—or it may be tried by shingles put together for the purpose, and then exposed to the fire.

FACTS IN PHYSICS.-Gold beaters, by hammering, reduce gold to leaves so thin that 282,000 must be laid on each other to produce the thickness of an inch. They are so thin, that, if formed into a book, 1500 would occupy the space of a single leaf of common paper.

WATER COLOR FOR ROOMS.-Take a quan- One pint of water converted into steam tity of potatoes and boil them; then bruise fills a space of nearly 2000 pints, and raises and pour boiling water upon them until a the piston of a steam engine with a force of pretty thick mixture is obtained, which is to many thousand pounds. It may afterwards be passed through a sieve. With boiling be condensed and re-appear as a pint of water then make a thick mixture of whiten-water. ing, and put it to the potato mixture. Το give color, if white is not wanted, add different colored ochres, lampblack, &c. according to circumstances. This paint dries quick. ly, is very durable, has a good appearance to the eye, and is moreover very cheap. . [London Paper.]

"In making railroads with timber, the posts or piles are liable to decay earliest at the surface, or a little above and below the surface of the ground, because the effect of heat and moisture there combine.

"To guard the post from this effect, I prevent the contact of earth with this part by means of stone laid close around it; and to keep the rain out from among them, I set them in water-lime-mortar, or in Roman cement, applying it to the wood as well as stones: I also use sometimes, in the upper stratum especially, a cement made of pitch and lime, when the kind of timber is congenial, pitch being adhesive and lime indestructible. In this manner may On the New-York and Erie Railroad. By J. be used the fragments of the quarry and coarse L. SULLIVAN. [For the American Railroad gravel, to form an artificial rock, surrounding precisely that part which is naturally most exJournal.] TO THE EDITOR,-It appears to the under-posed to the causes of early decay. The stone keeps the wood cool, the cement keeps it dry. signed that the article in your last number failed Again: when the bearing rail is of timber, surto do justice to the great subject of the Railroad mounted with iron plate, the wood is liable to from this city to Lake Erie, in some respects. become heated under the iron from the effects of I subjoin a short specification of an improve-iron rail may be thus loosened, and any comthe sun's rays thereon, and to shrink, and the position applied for the purpose of protecting

HAMILTON'S PATENT SAWING AND BORING MACHINE. We have experienced much gratification in examining this useful labor-ment in forming the least expensive railway saving machine; and we are perfectly sat. durably.

the surface of the timber from sun and rain, may be liable to be worn away by the movement or action of the iron rail under passing Harlaem; that a branch there inclines by Har-pressure. In order to prevent this and to give the iron rail firmness in place and bearing, I laem Valley to the North River, and follows its give the surface on which it rests the faculty of shore to a crossing to Sloat, in Rockland. solid resistance to the pressure of the iron rail, The passage across in winter time can be by driving into the wood at least two rows of of ascertaining the precise amount of labor kept open for steam railway deck ferry-boats, small nails evenly, their size from one to two and expense which this machine will save, by an application of machinery that I can satis- the weight of load, say about one inch, giving inches long, and distance apart according to but we venture to hazard the opinion that a factorily explain, to break the ice and keep a ca- all the nails relative level very near the surface man and two apprentices will accomplish nal through it open. After reaching Ramapo the of the bearer. And as the percussion by which more in twelve hours than forty experienced journeymen can accomplish at the same work route is a gradual ascent of this valley at 12 feet nails are driven is a much greater force than the passing pressure of loads, this pressure during the same period of time. It is withal in the mile, to Chester and Florida, 24 miles. will not settle the nails deeper in the wood, one of those inventions which require no From thence, crossing the outlet of the drowned but they resist it effectually, and prevent the extraneous aid to bring it into immediate lands, the route gradually ascends to Deer Park compression of the surface, and the displaceusefulness. The proprietor has commenced Gap, and descends to and crosses the Hudson ment of any defensive composition, as pitch working it daily, and in a ware-room adjoin- and Delaware canal; from whence the line and lime, that may have been applied under the ing the machine he offers for sale its pro- follows up the Delaware shore at a gradual as- firmly into contact with the heads of the nails, iron plate rail, which will have been drawn duce at from thirty to fifty per cent. less cent to Deposit, where it is nearest the Susque- by means of the screw bolts and nuts, with than the market price. This simple fact and hanna. which it is fixed on, passing through the timthe certainty that the work is in all its parts A railroad thus constructed is guarded By this route it takes up the coal trade at more perfect than that manufactured by hand, the mouth of Lackawana branch, and carries effectually against the working or yielding so has produced a demand more than equal to prejudicial to durability and good operation. it to the west, and in the four or five months the supply. "And I consider the principle of this improvement as aforesaid to be the combination of The machine is admirably well adapted to of winter brings it to this city. any sort of sawing that is usually done by It is evident that no railroad ought to be un-water-lime (or Roman) cemented stones surrounding posts or piles, and the nailing the top hand or cross-cut sawing. Tenons, mitre. dertaken unless it will give immediately an or bearing surface of timber for effective hardjoints, &c. are cut with the greatest preci-ample revenue to stockholders, unless by the ness with railroads." sion. In all sorts of pannel work and small State. By this plan (without preventing a framing it will be very useful. It is pecu- branch to the centre of Sullivan county,) a "Philadelphia, April 17, 1829."

isfied that it is destined to be of great public Permit me to suppose that there is a railroad
utility in cheapening the price of those arti- proceeding from the heart of this city north to
cles which are in use by all classes of so-
ciety, and will at the same time be a source
of great profit to the ingenious mechanic
who has invented it. We have no means

ber.

J. L. SULLIVAN.