SCIENCE AND INVENTION.

Gisborne Times, Volume XXIX, Issue 3195, 15 April 1911, Page 3

SCIENCE AND INVENTION.

FRENCH BUTTERFLY FARMS

There are in France, butterfly farms, the object of the farmers being to rear rara genera of the Bombycidae, the silk-Avorm family. By crossing, some new varieties have been obtained, and these are much sought after by museums of natural history. Endeavours are also being made in France to accimilate species of - silkAVorms indigenous to other countries. The farms contain oaks, ailanthus trees, pines, plum trees, castor oil plants, and other plants, the leaves of AvliicH serve as food for caterpillars. Cocoons are hatched on branches protected by gaijz© and for tlie sake of uniform temperature the insects are often kept in a room until after the first moulting, Avhen they are placed on bushes in the open air,"and protected from birds by coverings of muslin or Lille. THE SPEAKING CLOCK.

There is nothing outwardly remarkable (according to Das Echo) in the appearance of the ingeniously constructed time-piece known as the “time-stating clock.” But every quarter of an hour an agreeable voice issues from it, announcing the correct time, as 12 o’clock, 12.15, 12.30., etc. The works of the clock actuate a stout belt, which runs over a roll connected Avith the sounding box. Upon this belt, or rather film, the hours, Avhich have been recorded by a phonograph, are impressed by galvanisation on a copper plate. The mechanism Avhich moves the hands is connected Avith the speaking device, and this Avith a funnel re-enforces the sound and projects it outward through a. finely grated opening attached to the narrow side of the clock. At night a touch on a lever reduces the clock to silence. But if one Avakes and Avishes to knoAV the hour without' striking a light, an easily found button is pressed and the clock immediately states the time. The speech film is practically indescruct'ible and occupies very little space, since, because of its elasticity, it may be Avound upon a very small roller. ARE THE STARS COUNTLESS ?

The universe of stars may be without end, or it may have a limit Avith nothing beyond, hut either alternative is unthinkable. Each increase in the power of the telescopes or in the exposure of photographic plates has added new stars—suggesting an infinite number. But nothing is proven, and an astronomer points to some recent Russian observations that give possible evidence that the number is not endless. Photographs were made in four different parts of the sky Avith a telescope of 13in aperture, in the constellation Perseus 250 stars Avere shown by an exposure of the plate for six minutes, 2000 in two hours, and 11,000 in 30 hours ; near Niu Argus, 10,000 in about four hours, 50,000 iii 12 hours, and 100,000 in 24 hours; and in the ring nebula in Lyra. 1000 in one hour, 6000 in 10 hours, and 10,000 in 20 hours. In the Pleiades, hoAvever, 160 stars Avere shown in an exr posure of 18 minutes, 600 in three hours. 1300 in 10 hours, hut only 1750 in 25 hours. This small increase in the number of stars picked up hv lengthened exposure suggests a thinning out, and that in the direction of the Pleiades the nrohings of astronomers may have nearly reached the limit of stars in existence.

SEA AVATER AS LIQUID FOOD. It has hitherto been supposed that marine animals derive their food from each others’ bodies, and, in the last analysis, from plants,-says Prometheus. A few years ago, however, Puettner discovered that the sea contains dissolved food materials, upon Avhich some marine animals, notably sponges, appear to Ha t g exclusively. A given volume of sea Avater contains in dissolved condition 24,000 times more carbon than it contains in the form of organisms. Puettner proved that one species of sponge, if, it Avere compelled to live upon ready-formed food, could obtain in one day only 1-2300 of the quantity of carbon which it consumes in that time; and in order to obtain even this small quantity, it Avould have to fish over 20 times the volume of sea Avater which Avould suffice to supply it Avith all the carbon it requires in the form of dissolved complex carbon compounds. A'ery interesting in this connection is the observed fact that comparatively small quantities of readyformed food ‘are found in the digestive cavities of the loAver marine animals. Hence sea Avater is, for a great many invertebrate animals, a nutrient fluid from Avhich they absorb food, as the cells of animal tissues absorb food from the bodily fluids, animal parasites from the media in Avhich they live, and all plants from their emnronnmnt. The sea is an inexhaustible reseiwoir of food.