SCIENCE NOTES.

New Zealand Mail, 21 February 1901, Page 18

SCIENCE NOTES.

BENEATH THE SERFACE. One of the most important scientific events of the ndw century is expected to be the voyage under water across the Atlantic of a new Holland submarine boat. Mr Holland, with a small crew, will try the experiment in February, starting in rough weather. This journey of 3500 miles under the sea is projected to test once for all the capacity of the submarine boat to care for herself on a long trip under the most unfavourable conditions. The vessel will be driven by a gasoline engine of the Daimler pattern which Count Zeppelin uses in his navigation of the air.

€3 SUPERSEDING CABLES. Wireless telegraphy has reached a new stagol of development, and Marconi expects that he will soon be able to send messages across the Atlantic. The mastproblem has been solved. The “Daily Express’’ says : ‘infinite capacity for taking pains’ has enabled him to construct apparatus whereby he can lengthen the air waves to an almost unlimited extent. Furthermore!, by the same ingenious device the sound-waves will travel close to the! surface of the ocean over the whole distance, thus circumventing the dreaded difficulty presented by the curvature of the earth. Hdnce the masts erected at Southampton and Long Island need not, it is now contended, be higher than the rocf of a New York ‘sky-scraper.’ Perhaps, after all, there will be no necessity to lay the Pacific cable, as Marconi’s success undoubtedly means that the submarine cable will be superseded, and that at a hundred-thousandth part of the cost.

MICROBES IN DUST. When dttst in the streets is watered in summer, it is for the purpose cf laying it and preventing it from floating about in a disagreeable and insalubrious manner. It is also for the purpose of infusing a certain amount of moisture into the air by the evaporation, of the water. But it may be questioned whether this mode of proceeding is not favourable to the multiplication of germs contained in the dust, whictx dryness, combined with the action of solar light, would have otherwise destroyed, thus counteracting the really dangerous and insalubrious element of dust. To settle these questions. M. Mazuscliita has made a series of bacteriological examinations of dustpicked up from the streets of Friburg, some of which was regularly watered, and the rest left dry. A gramme or half a gramme was placed in a litre of sterilised water, and with one; or half a cubic centimetre of this dilution gelatine patches were immediately made, and afterwards used for enumerations. M. Mazuschita found that the number of bacteria iruthe watered dust was more thaan uo-u----ble that in the dust that had not been watered, the average proportion per gramme of dust being 1,204,946 to 589,857. At the end of four fine days the proportion was about 2,211,550 to 1,693,000, and at the end of 26 days of the same fine weather it was 97,333 to 37.250—that is to say, in the' watered dust 956 per thousand of the germs had disappeared ; in the dust not watered 981 per thousand had disappeared. The difference is not great, but, after all, the watered dust contained 1 more than double the number of bacteria as compared with the non-watered dust. The germs that were found in the watered dust were not all of the same kind as those in the non-watered dust. Tljey are-re-presented by various varieties of the staphylococcus. They are a species that resist very strongly light and drying. In his conclusion, M. Mazuschita considers that watering the streets is not tobe recommended from a hygienic point of view.

THE USE OF KINEMATOGRAPH. The value of the! kinematograph as an aid to clinical teaching is not yet recognised in England, although the German as well as the French savants seem ready to take advantage of some experiments recently conducted at Kiel by the celebrated French surgeon, Monsieur Doyen. He pointed out that '‘no work on surgical practice was able to describe operations so carefully and fully as to avoid the possibility of erroneous treatment by the operator.’’ By means of the kinematograph and its rapidly recording film, Monsieur Doyein was enabled to show various kinds of operations in their entirety, from the first incision of the surgeon’s knife to the application of the bandages at the completion of the operation. Such a series of pictures should be invaluable, for from the crowded benches cf the operating theatre little or nothing is seen of the actual steps of the operation, except by those in the immediate vicinity, and of necessity these are few in numbex-

THE ECLIPSE CINEMaTOGRAPHED At the Egyptian Hall in London, one of the principal items of the cinematograpli exhibition is a film of the last solar eclipse, taken at the station in North Carolina by Mr J. N. Maskelyne, of the Royal Astronomical Society. The films give a very interesting idea of the character of the eclipse, and the inner coronal ring long previous to and after

the' totality of the eclipse is reproduced with greac distinctness. The photographing of the slender partial phases and the corona, in order to obtain correctly graduated exposures on biographic films, necessitates the placing of a thin wedge of yellow glass, backed by a similar wedge of plain optical glass, in front of the film, so as to move longtitudinally. The camera is provided with a small ruby glass window, and through this the operator is able to follow thet diminishing eclipse crescent, and to maintain the regular intensity of the image by gradually moving tne wedge along.

GROWTH OF ROOTS. Mr Pearson writes as follows in “Knowledge” : “The fact that roots grow downwards is so well known that mention of it may seen superfluous. This habit is due to the influence of gravity. It is easily noticed that the main root (produced by the combined growth of the radicle) "is more strongly influenced by the force of gravity than are its side branches, for while it strikes a course which is, in the main, towards the earth’s centre, its branches make a considerabls angle with it, and frequentlv grow in a horizontal direction. Consequently the roots are able to exploit a much larger area of soil than would be possible if the branches and the main root were equally amenable to gravity. A further peculiarity in the growth of most roots is that they shun the light and take the shortest course to dark or shady places. On an ivy stem the clinging roots by which it is attached to the wall or tree all emerge cn the shady side of the stem and proceed at once to bury their sensitive tips in the nearest hollows of the support. These two characters possessed by most roots, viz., a tendency to grow (1) in the direction of gravity, and (2) away from the light, cause them to penetrate the soil in which their quest (mineral food) is to he found.

THESE WONDERFUL A NTS

An American naturalist describes a species of ant, the peculiar feature of whose domestic economy is, that they cultivate near their dwelling what may be called “Mushrooom Gardens.' It appears that they cut and transport into their subterranean cellars large pieces of leaves, which are! there divided into smaller' fragments, and ultimately reduced to a fine pulp. “This pulp is heaped up, and scon becomes invaded by the mycelium of a fungus. The' mycelium is kept aseptically clean—i.e., free from all species of fungi and even from bacteria—and induced to grow in an abnormal way by bringing forth minute swellings which constitute the- only food of the ant colonv.”

LLOYD S AND ETHERIC SIGNALLING. It is announced that “Lloyd’s” has determined to adept experimentally the reporting of vessels by “etheric” signalling at Inishtraliull, north of Ireland. It is expected that the installation will be ready by the middle of January. Arrangements are also being made for night signalling, as well as day, at Kildonan, Arran, Scotland. Presumably it is meant that the wireless system of telegraphy will be adopted, but lio doubt the usual signalling will be carried on while the “experiments’’ are being made.

AN EXPERIMENT 1a FORESTRY. Experiments in forestry are being carried on in California, the idea being to determine as neiar as possible the value of timber to a water-shed. The rainfall in the lands which have been set apart for the relative amount of run-off is carefully estimateid. The experiments are being conducted on a very extensive &pale, so they will undoubtedly prove a* great value-