under the superintendence of this committee. At the same time the Artisans' Dwellings Act came into operation, and the provisions of this Act, with powers possessed by local Acts, have furnished the committee with the necessary authority for altering the old ash-pit and enforcing the construction of new ones according to the plans which have been adopted. In the construction of ash-pits the object of the committee was to prevent as far as possible the decomposition of the excreta, and consequent generation of gases passing off into the surrounding atmosphere; and as decomposition is accelerated by moisture, they determined that all ash-pits should be made dry, excluding the rainfall by covering them over, and the drainage from the yard by requiring the floor and walls to be made water-tight; they required also that the ashes from the pit should be placed daily in the ash-pit for the purpose of condensing, as far as possible, the ammoniacal and other gases, and preventing organic matter impregnating the air in the immediate vicinity. In addition to these arrangements it was foreseen that in summer time, when decomposition is most vigorous and the supply of neutralizing ashes most scanty, a closed ash-pit might become a greater nuisance than an open one; and a ventilating-shaft or chimney was determined upon, to be carried from the top of the ash-pit up to the side of, and a little above, the eaves of the house for the purpose of carrying off all the gases and light vapours and allowing them to mix with the surrounding atmosphere at an elevation which would not injuriously affect the inmates of the dwelling.

In attempting these improvements the committee met with considerable impediments the covered ash-pit and flue had a hard struggle for existence; the council was sceptical, especially on the efficacy of the flue. It was to little purpose to assure the members that as the emanations from the ash-pit would, from the warm ashes of the kitchen and the fæcal matter, be of a higher temperature than the surrounding air, they must necessarily ascend and pass off at the highest point of egress, and, if there was no opening but the flue, then up the flue. The reply was, they might not do so. A flue had been connected with a covered ash-pit for a considerable time, and was found to be most effective; and it was urged that all other flues under similar circumstances would also be efficient, just as surely as heated air ascending one chimney would ascend all chimneys. The evidence was not deemed sufficient. The committee was authorized and required to have a number erected, and meanwhile the enforcement of the regulation was suspended. When at length the council, satisfied by the evidence adduced, authorized the committee to proceed, another obstacle presented itself. The property owners (that is, the owners of cottage property), having chiefly formed themselves into an association, rose in arms against the change; they declared that the cost of making the alteration would be £8 to £10, and that the rents must be advanced 1s. per week to carry out this new plan of the committee. They declared that, in the opinion of practical and scientific men, the ventilating-flue would be perfectly useless, that the noxious gases would not escape through the flue, but would overflow into the back yard, producing greater evils than any it was intended to remedy; and in a report of the executive committee of the "Associated Property Owners' Association," issued in December last, it is declared that, after nearly twelve months' experience and from consultations with gentlemen well able to form an opinion, they are more than ever convinced of its uselessness; and they promise at an early date to have the opinion of scientific men put in an official form in the nature of a report, which would be submitted to the health committee. What the opinion of these scientific men, upon which the property owners rest their case, may be cannot be ascertained, as no report has ever been presented; but it is worthy of remark, as illustrating the complexity of our legal procedure, that with all the powers possessed by the corporation in its many local Acts, and the stringent clauses of the Artisans' Dwellings Act, some of these property owners have succeeded in delaying the reconstruction of privies and ash-pits in connexion with dwellings declared by the officer of health to be unfit for human habitation for a period of nearly twelve months. Notwithstanding these obstructions, the committee has continued its operations. Every new house erected in the city is required to provide a water-tight covered ash-pit with ventilating-flue; and, taking the worst of the old ones, just about 270 have been reconstructed on the new plan, or as near 1870.

15

it as practicable. The results have been most satisfactory. I quote from a report of the health committee, giving to the council the result of an inspection of a number erected as a trial by the committee:-"It was found that the yards at the back of the houses, and the privies themselves, were entirely free from any offensive odours."

The contents of the ash-pits were dry; the surfaces of the yards were clean. When the hand was placed in the opening of the seat a current of air was perceptible; when a piece of brown paper was lighted and then blown out, so as to produce considerable smoke, and the paper then held over the grid in the wall of the privy, the smoke was strongly drawn down into the ash-pit; the same when applied to the seat of the privy. No smoke escaped at the opening of the seat, but all passed up the flue and mixed with the atmosphere above the roof of the house. The information from the occupants of the houses was most interesting. Some of them stated that whereas before the alterations were made they never opened the windows of the back bedroom in consequence of the stench that came into the room from the privies and ash-pits below, they now opened them daily, and got the rooms ventilated, and that, although formerly they were scarcely conscious of the disagreeable stench from their neighbours' premises, now their own were cleaner these fæcal smells affected them. The officer of health in his report, and as the result of careful inquiries, states that where the new form of ash-pit has been adopted, whether in old or new houses, there was not last summer a single case of diarrhoea or fever in the families of any of the occupants, although the former disease prevailed to a considerable extent in neighbouring families; the testimony of many house-owners is to the same effect. It is found that in new dwellings the cost of the new privy amd ash-pit is less than the old one; while in the reconstruction in old property it is much less than, in their fears, they had anticipated. In the appendix to the report of the medical officer of the Privy Council just printed, Dr. Buchanan and Mr. Radcliffe made the following remarks on the Manchester system:-" We inspected a midden-closet arranged on this plan in a position where the advantage of careful superintendence was secured for it, built according to the requirements of the corporation-roofed, drained, and ventilated by a shaft carried up above the eaves of the adjoining building. The closet or privy used by a single family only opens into a small yard, 8 ft. 2 in. across at the widest part, and faces the living room of the cottage occupied by the family. A urine catch-pan was fixed beneath the privy-seat; the midden was twothirds full of ashes and refuse, the latter cast in beneath the hinged seat, and no excrement was exposed to sight. As it contained fifteen months' accumulation of excrement, ashes, and house-refuse, its condition might not unfairly be regarded as similar to that of a closet emptied more frequently, but used by several families. There was no smell of excrement, nor, indeed, any marked odour about the privy, though on the same day (during a frost) in unimproved privies about the town there was notable stink. A current of air, as we determined by experiment, passed down through the aperture of the seat and upwards through the ventilating-shaft. The occupants of the house averred that no foul smell was at any time experienced by them from the closet. The removal of the contents of the ash-pits has been managed by the corporation since 1845. There are about 38,000 ash-pits of all sizes in the city, some large ones requiring to be emptied only once or twice a year; on an average, the contents will not be removed oftener than from two to three times in the course of a year. In the newly constructed ones, the size being so much reduced, the contents require to be removed more frequently; but the health-committee, regarding the matter in a sanitary point of view, not in an economical one, consider even the size of the new ones too large, and are gradually aiming at a size that will necessitate the removal of the contents every two or three weeks; but it is difficult to effect great changes all at once. Many people object to the emptying of the ash-pits frequently, or until they are filled with ashes, excrement, and refuse, and frequent removal can only be effected by limiting the space in which this refuse matter is contained. The ultimate aim, then, of the health-committee is to provide for every cottage a privy and small ash-pit, not sunk deep in the ground and perfectly water-tight, excluding the water from the yard and slops from the house, and covered over to exclude the rainfall-excluding also,

if possible, all refuse matter except the small ashes from the fire, and securing that these ashes shall be placed upon the excrement daily. In every case the ash-pit is placed as far from the entrance-door of the house as possible; and as in all new houses a yard-space of considerable size is required, generally the privy and ash-pit will not join up to the walls of the house, and in every case where it does so a strong flag is placed between the wall and the privy; and as the floor is sunk beneath the level of the floor of the dwelling, percolation will be entirely prevented. In addition, a ventilating-shaft must be carried up to the eaves of the house, the horizontal portion of which may form the coping of the separating wall between the two houses, and the area of this shaft must not be less than eighty-one square inches. A drain and grid are also required in the yard to carry off the water and slops of the house into the street sewers. Already upwards of 1500 have been erected under the supervision of the committee; the occupants are perfectly satisfied, and are constantly expressing their approval. The opposition of the property owners is subsiding; and although it will take many years to alter and improve the 30,000 old ones in the city, the committee and the officer of health feel confident that every step in this direction will tend to reduce the death rate and improve the health of the inhabitants."

Pneumatic Dispatch.-On Pneumatic Transmission through Tunnels and Pipes*. By ROBERT SABINE.

The author, after giving the result of investigations into the motions of bodies through tubes for this purpose, and the formulæ which he had arrived at, said that these would show that small pneumatic tubes could be worked more advantageously than large ones. The great convenience of and practical facilities for working small letter-carrying tubes have been amply proved by the extensive systems already laid down, in Paris, Berlin, London, and in other towns, as adjuncts to the telegraph services. Tubes of somewhat larger diameter, such as those proposed some years ago by Mr. A. E. Cowper for the more speedy distribution of metropolitan letters to the branch post-offices, would undoubtedly work satisfactorily. Even still larger tubes, if of moderate lengths, might also be found useful for a variety of special applications; for instance, in the transport of light materials between the different parts of a factory supplied with steam-power. He did not believe that a pneumatic line working through a long tunnel could, for passengertraffic, ever compete in point of economy with locomotive railways. A pneumatic railway is essentially a rope railway. Its rope is elastic, it is true, but it is not light. Every yard run of it, in a tunnel large enough to carry passengers, would weigh more than cwt. And a rope, too, which has to be moved against considerable friction, in being compressed and moved wastes power by its liberation of heat. In a pneumatic tunnel, such as that proposed between England and France, in order to move a goods-train of 250 tons through at the rate of 25 miles an hour, it would be necessary to employ simultaneously a pressure of 1 lb. per square inch at one end, and a vacuum of 13 lb. per square inch at the other. The mechanical effect obtained with these combined (pressure and vacuum) would be consumed as follows:

The resistance of the air, therefore, upon the walls of the tunnel would alone amount to 93 per cent. of the total mechanical effect employable for the transmission, while the really useful work would be only about 5 per cent. of it. And to compress and exhaust the air to supply the above items of expenditure of mechanical effect, engines would have to exert over 2000 horse-power at each end during the transmission, even on the supposition that the blowing-machinery returned an equivalent of mechanical effect such as has never yet been obtained. This * Published in extenso in Engineering,' Sept. 23, 1870.

would not be an economical way of burning coals. It is desirable, nevertheless, from an engineering point of view, that the merits and demerits of pneumatic parcels-lines and pneumatic passenger-lines, which have been repeatedly suggested during the past half century, should be thoroughly investigated. The works of the Pneumatic Company in London, which are approaching completion, will happily settle the question as regards parcel-tubes; whilst the pneumatic passengerrailway, which, he was told, is in rapid course of construction under the streets of New York, will very soon either inaugurate a new era for city railways, or be written in the long list of unsuccessful experiments.

On a Submarine Ram and Gun. By MICHAEL SCOTT.

On Ships of War of moderate dimensions. By MICHAEL SCOTT.

On the Machinery and Working of Submarine Guns. By MICHAEL Scott.

On the Sewage of Liverpool and the Neighbourhood.
By JAMES N. SHOOLBRED, C.E.

Liverpool at present contains about 520,000 inhabitants, and the suburban districts round it about 80,000 more; in all 600,000.

Of these by far the greatest number reside on a strip of land of no great breadth, running along the river Mersey and its estuary, and sloping gently down to them. The close proximity of this rapid tidal stream, as well as the great facility afforded by it for the ready disposal of sewage and other refuse, will account for the predilection already shown for the water-closet over the privy system; and which predilection is annually becoming still more manifest. There are at present about 40,000 water-closets against 30,000 privies in the district..

The borough of Liverpool has expended about £900,000 in drainage and sewerage works. Of this, £300,000 may be set down as necessary for the conveyance of the contents of the water-closets. If this sum is capitalized, and a large allowance made for deterioration, then an annual amount of £60,000, or about 2s. 4d. per head of the population, may be taken as the cost of getting rid of the wet sewage of the town.

The midden, or dry sewage, together with the contents of the ash-pits attached to the houses having water-closets, amounts within the borough to about 140,000 tons in the year. This is removed by rail and by canal, and disposed of at a cost of about £21,000, while the amount realized by the sale of the refuse is only £8000; thus causing an annual loss to Liverpool of £13,000, or about 6d. per head of the population, in order to dispose of its dry sewage.

Several propositions have from time to time been made, especially since 1866, to utilize the wet sewage of the town by irrigation over some light soil about 10 miles distant to the northward, and near to the sea-coast; the land is of very considerable extent, and favourably situated for the purpose.

However, nothing as yet, beyond a trial experiment, so far successful, has been effected, and that upon a very small scale. Further steps with the same object, but in a different suburban district, are, it is understood, about to be taken.

The ready market which Liverpool in itself affords for the sale of the vegetable proceeds of this irrigation, and consequently for its success, is a further stimulus to reduce by this means the present annual cost to Liverpool in getting rid of its sewage and refuse.

Liverpool may, however, be said even now to be much favoured by nature in this matter; inasmuch as the burden falls much more lightly upon it than upon many other large towns, which have enforced against them by the arm of the law the unpleasant consequences this question may sometimes bring with it.

On Mechanical Stoking. By JAMES SMITH.

On a New Safety-lamp. By W. E. TEALE.

Description of the Hydraulic Bucketting-engine for the Herculaneum
Graving-dock, Liverpool. By PERCY WESTMACOTT, C.E.

The application of hydraulic power to gates and capstans &c. having already been decided upon for these docks, it was considered expedient to contrive the emptying of the graving-docks in conjunction with this same system, and thus save the erection of another steam-engine and plant for this special service, and at the same time secure a ready means of applying power at all times, especially to severe leaks. Some arrangement, too, was required that would overcome the inconveniences experienced in dealing with water charged with rubbish from graving-docks. The result was the construction of a machine upon a principle of bucketting large quantities of water at a time-devoid of clack-valves, gratings, or other parts liable to choking or injury by floating matter, and that could be lifted clean out of the water to give free access to all parts when required. By this principle the same weight of water is discharged at each stroke, and thus no undue loss arises from the application of a constant hydraulic pressure; nor does the strain upon the parts or the conditions in working vary with the fall of water in the dock. A scooped-shaped bucket attached to a piston-rod is plunged at an angle of slight resistance into the water, and by a self-acting arrangement is turned round at the proper level, filled, raised, and discharged over an apron. The bucket holds 14 tons of water. Two discharginglevels are provided.

It will be seen that when the bucket is up all essential working parts are out of the water, and therefore quite free of access.

The minimum lift at the high-level discharge is 7 ft., and the maximum 23 ft. The usual average speed of the bucket in plunging or lifting is about 3 ft. per second.

The coefficient of effect obtained by this engine is as follows:-At 7 ft. (minimum) lift 4; at 23 ft. (maximum) lift 6; average 54. The loss occasioned by the choking of passages and gagging of valves or paddles is altogether avoided by this system, which, for this reason, is peculiarly well adapted for sewerage purposes.

On Street Management. By F. WILSON.

APPENDIX.

On the Vegetable Products of Central Africa.
By Lieut.-Colonel J. A. GRANT, C.B., F.L.S.

The country embraced in the remarks made by the author comprises that traversed by the late Captain Speke in his journey to the sources of the Nile, 1860-63. The plants collected were made over to the Royal Herbarium, Kew, and were classified there by Dr. T. Thomson. They are to be described in the African Flora' by Professors Oliver, Lawson, Masters, and others. Notes and drawings of the majority of the specimens were made on the spot, and from these notes the author had compiled this paper. He described, in the first place, the forests of the low lands, which consist of trees which are commercially of small importance. The species are numerous, and for nearly all of them the natives seem to have names. The author then described at considerable length the uses made by the natives of the roots, bark, leaves, fruits, seeds, and grains of numerous trees, shrubs, and plants as medicines, foods, household utensils, fishing-implements, and the like.