« AnteriorContinuar »
- - and a shilling per volume more for binding decently Apropos to telescopes, Mr. Cowper Ranyard lately in cloth. Such being the case, the anti-climax to read to the Astronomical Soeiety a note on the which I have alluded is simply inconceivable. On blurred patches that appear in the splendid photoapplication being made for copies to be sent to our graphs of the sun taken by M. Janssen at Meudon. public libraries, the Government has declared that it Janssen is himself inclined to attribute them to solar cannot afford these few ninepences per pound and clouds or gaseous matter above the photosphere, but shillings per copy.
Mr. Ranyard has made some experiments indicating Compare this with the proceedings of the Go. that they have their origin within the telescope itself, vernment Printing, Office at Washington, whence and are due to heated currents of air in the tube. He are issued the noble records of “ The United States produced exaggerated representations of these in the Naval Observatory," &c. These are not only dis form of ripples by placing a heated body inside his tributed freely to the American public libraries, but telescope. The difficulty of maintaining a perfect are sent across to the scientific libraries of Great calm within the tube of a large telescope must be Britain, and not only to them but to individual great, and the sensitive film used for these instanmembers of the scientific societies. I have a very taneous photographs cannot fail to display any disvaluable series of these reports, and of the Reports of turbance affecting either the transparency or rethe “ Department of the Interior,” and other works fractive power of the air in the telescope. I think issued by the United States Government from their the question as between these two explanations might Printing Office at Washington. These are sent over easily be settled by taking several pictures of the sun to me through their agent, and carriage-paid to at short intervals apart. If the light patches or blurs London, upon no other asking than that of replying are due to cloud-matter in the sun they should to an official letter enclosing a list of works from appear at the same place in all the pictures, seeing which I am asked to select those I desire to have. that the space represented by every square milliGenerally speaking they are invaluable as original metre of such pictures is so enormous that no cloud records of most important and laborious scientific could travel to a sensible distance on the picture in any investigation. All Englishmen desiring to be patriotic short period of time ; while, on the other hand, the must be bitterly ashamed of this melancholy contrast. atmospheric irregularities within the telescope must
The present favourable position of the most won be visibly shifted during small fractions of a second. derful and beautiful of all the heavenly bodies, the planet Saturn, with its mysterious ringed appendages, reawakens an old project that I have often longed to
DESCRIPTION OF A CONVENIENT FORM carry out, viz., the establishment in a suitable part of
OF LIVE-CELL FOR: OBSERVATION London of a popular observatory. I don't mean an
WITH THE MICROSCOPE, AND OF AN establishment with amateur observers pretending to
INEXPENSIVE MICROTOME. do original astronomical work, and thereby supplementing or superseding the Greenwich business; but THE main drawbacks of most cells for the obsersimply a good astronomical peep-show, where millions 1 vation of living objects are that they either of people who have never looked through a powerful leak, or are very difficult to clean. The undertelescope, and otherwise never would do so, might described form, which I have lately contrived and have an opportunity of seeing for themselves some of used, obviates these defects, and may therefore be of the magnified glories of the heavens. I believe that interest to the readers of SCIENCE-Gossip. It is of it might be made commercially self-supporting if very simple construction, and can be made up at a well done, and all pedantry severely excluded. No trifling cost by the help of any ordinary metal worker. mathematical work could be done nor need be at. Take a stout ground-edged glass slip, and have tempted. Both reflecting and refracting telescopes fitted to it two sheaths of thin brass, about 4-inch equatorially mounted with the simplest of efficient wide. These should be made to fit closely, but not clockwork would be required ; and one telescope so tightly as to prevent the glass slip from sliding should be provided with spectroscopic appliances. easily through them. To the middle of one end of The physical phenomena are all that the popular each sheath is soldered a small brass arm (shaped as visitor would desire to see, and the fact of having in Fig. 2), carrying a fine screw on one arm, which, once seen the most striking of these would leave a when secured in position, projects about l-inch life-long impression on all intelligent men, women, beyond the end of the sheath. and children. A small charge, with proper regula- A piece about if inch long, cut off a thin glass tions as to time allowed at each instrument, would slide, and a thick india-rubber ring (those used for cover all expenses, including a modest salary to the Cod's patent soda-water bottles serve excellently) showman-I beg his pardon--the director. The sun completes our requirements. and moon should be shown first with a low power to To put the parts together, slip the sheaths, one on display all the disc, then with a high power for | to each end of the glass slide, with their two little particular details.
screw arms projecting towards each other. Now cut a small piece out of the circumference of the india | It consists of a block of well-seasoned wood, rubber ring, and place it on the slide between the 5x3x3 inches. At it inch from one end of the sheaths, with the opening towards one of the long block a hole is bored of such diameter as may be sides of the slide. Place on top of the ring the short necessary to admit the cylinder of a pewter syringe piece of glass, and slide the sheaths towards each of about inch internal diameter. This hole runs other, till the small screws project over its ends. vertically from the upper to the lower surface of the Then, by turning down the screws, the ring is com block. Across the opposite end of the block is cut pressed between the two pieces of glass, and a perfectly a horizontal notch, if inch deep and wide. Cut off water-tight cell results. By using rings of different the nozzle end of the syringe, so as to leave a piece thickness, cells of every convenient depth may be of tube three inches long, and cut the handle off the obtained.
plunger so as to leave only the piston part. This When one has finished working with it, the whole | should be packed as neatly as possible, and have
Fig. 5.-Upper Surface of Microtome. soldered to its upper surface a small Z-shaped piece of tin, so as to give the parapin a firm hold on the piston.
Cement the tube into the hole in the block with shellac or elastic glue, so that one end projects about the thickness of a glass slide above the upper surface, and cement on to the upper surface of the block, along each side of the projecting portion of the syringe, an ordinary ground-edged glass slide, taking care to choose a pair of equal thickness, and with well-rounded edges. Now procure a fine screw running on an oblong-nut : the nut to have a hole to take the head of a wood-screw at each end, and secure it by means of a couple of screws to the under surface of the block, so that the fine screw works up and down in the centre of the pewter tube. Get also one of the coarse iron screws with brass fittings, such as are used to fasten oldfashioned window sashes, procurable from
any ironmonger, and fasten this to the under surface of block, so that the coarse screw may work into the notch already described.
To use the machine, place it with the edge of a lath projecting into the horizontal notch. Then by screwing up the coarse screw, it will be firmly clamped to the table, and projecting beyond it, a position extremity convenient for working.
Now turn down the fine screw, and push the piston, with the finger, down through the tube on to it. The well is then filled with a melted mixture of five parts solid paraffin to one part tallow, and the object to be cut embedded in this. The sections are then taken in the usual way, the two
Fig. 4.-Inexpensive Microtome. Vert. section.
thing can be taken to pieces in an instant and cleaned. If a well-polished piece of glass, free from flaws, be chosen for the upper plate, its thickness will not be found to interfere very materially with the performance of any power below 4-inch.
While on the subject of cheap apparatus, I will describe a form of microtome which can be made by any one, with a slight mechanical turn, for about eighteen-pence. In many essential points it is almost identical with that of Mr. A. B. Chapman, described in your June number, as, however, I constructed and used it more than ten years ago, I must claim to be guiltless of plagiarism.
ground edged slides acting as the guides to the form sori, seated on scarcely perceptible spots, on the razor.
underside of the leaves (only rarely on the upper With one constructed in this way, I have procured side); the sori were scattered, or irregularly grouped, sections finer than I have got with any other non- occasionally in orbicular clusters, round or oval, freezing machine.
averaging 300 u in diameter, convex and elevated. I have one further limit to add. In cementing on The epidermis persisted round the sori, forming a the two glass slides, take care that, if not quite somewhat dome-shaped investment, ruptured at the horizontal, they may tend to form a V, rather than summit, where it was pale in colour, but below darkan A with each other, as should the inner edges be brown, owing to the paraphyses showing through. the least higher than the outer, the razor will be These paraphyses, which formed the most striking very quickly blunted, whereas, on account of the feature, were arranged in a single ring, surrounding razor edge being, as a rule, somewhat curved, the the sorus, just within the persistent epidermis ; they circumstance of the outer edges being a little high is | were dark-brown, shining, oblong-cylindrical, enof no moment. Also do not be tempted to make larged at the apex (club-shaped), inclining inwards your well of large diameter ; 1 inch is quite as large a towards the centre, from 80-100 u long or more, and section as one is likely to want, and the smaller the about 12-15 u thick. (Figs. 6 & 7.) diameter of the well, the more even will the sections be. Within these were the uredo-spores, oval, obovate,
Of course a brass tube and plunger may be made I oblong, or roundish in shape, surrounded by a very
use of, if desired; but, somehow, I never got one to thick, colourless, warted membrane (Fig. 8, a); act as well as my old “sixpenny squirt.” Though I contents very pale yellow, with a few oily drops ; made many of them, one time and another, either 30-50 u long, and 20–24 u broad. No other spores for friends, or in the hope of improving the machine. than these could be seen in situ ; but, on scraping off a
G. M. GILES, M.B., F.R.C.S. few sori, a small number of meso-spores were observed, Peshawar. Surgeon Ind. Medical Service. which differed in being of a darker brownish colour,
and less or not at all warted surface; the transition from the uredo-spores to the meso-spores could be
clearly traced. (Fig. 8, b and c.) A persistent search A NEW BRITISH PUCCINIA.
revealed a few teleuto-spores, which were oval, not IN October last, Mr. H. Hawkes sent me, from constricted, smooth, and dark-brown; but so small I near Birmingham, a fungus upon the leaves of was the number that I incline to the opinion that Sonchus, which had the appearance of a Puccinia, these were accidentai intruders, and did not belong but in which he could find none of the characteristic to the same species. They might have been blown two-celled spores. A careful examination convinced on to the leaf from some neighbouring plant infested me that I had, in all probability, the uredo-stage of a with a Puccinia. (Fig. 8, d.) Puccinia hitherto, I believe, unrecorded in Britain, The plants on which this fungus was found were viz: Puccinia sonchi, Desmaz. First, to describe two small seedlings, not in flower, growing on rubbish the fungus in question :-It occurred in small puncti. | which had been thrown out of the canal in cleaning it ;