SCIENCE NOTES.

Otago Witness, Issue 2523, 23 July 1902, Page 68

SCIENCE NOTES.

— Lord Kelvin has recently published tho i "results of an investigation which he has j made to determine the absolute amount of matter in our universe. On account of the Uttraction of gravitation, every object m the Universe is in motion. The heavens look calm on a fine night, but in reality every j 6tar is in rapid motion through <>pace. Lord Kelvin's problem was to find how much material substance the universe must contain in order that the mutual attraction between its different part* should produce the Itar motions actually observed, assuming that the stars were once aC rest. He took as the limits oi our uni\er«e a distance such that the light of the mo«t distant star would take about 3300 years to reach ii=, though the i tavs tra\el witn a \elotity of 186,000 miles per second. The conclusion at which Lord Kelvin arnvo, i« that, if a mass of matter equal to 1000 million -mis were at rr-t in this almost infinite extent of space 25 mil- , Son years ago. and wa-, uiufoimly distributed ihrough it, tho different parts v oulcl by this \ iimp be moving on tlie average <U about the }ate actually measured by a«tronom< i=. In )ther worcU, reasoning from the pro-c ul velocities of stars in space, Lord Kthm )hows that the amount of matter in our jniveyg^ jfl >boufc gflUJ^ jjj fiiilS£ t-0 100Q Uxll-

lion sun*. As there are probably not more than 100 million ttar-; which can be seen or photographed, it follows that there must be 10 times as much dark material in the uni\erse as there i< bright Whether Lord Keh in's (onclusion-. are "accepted or not, there is abundant evidence of the existence of invisible matter m space; and the latest investigations seem to show that one star in every 10 or 12 has a dark ttar re\ol\ing round it. These dark stars can ive\cr be =een, but their existence is proved beyond doubt by the study of their influence upon the movement!; of tho bright stars, to which, according to an aiticle in the Lei=uie Hour, they are united by the bond of gravitation.

— That the head of a mountain should Vie blown away, a« was that of Kiakatoa in Augiifct, 1883," and that of Mont Pelct in Martinique a few week- ago, by the meie force of steam appear-, difficult to reali c e; but geologist-, generally regard this as the true explanation. "We can hardly doubt,"' sajv Frcfe.?»or Bouncy, "that steam is the main explosive." Actno volcanoes are constantly cmittifg steam, and M. Fouque. who = Uulipil an eruption in Ktna in 1365, com|jtin d t'lat tho moimtain di-rh lr-^ctl m 100 ditv» a- -ti.m 2.825.6G0 culm ya - of water, \\lioc\(i luis v.itihf-'l. o\o\i in qu'tH tlinf-, die (li,ii(l funning over ili^ i.,.!ir- of Etna and Vi^umu-, will not quo-tion the preatuLe oi steaca. The UiSicilltE. been Ui

understand how the water reached the burning mass in the volcano in view of the enormous underground pressures. But somehow the wates docs percolate to great depths, and apparently against high pressures. Professor Daubrc© had a c'-amber filled with steam at 285deg F.. and separated this from water by a slab of close fine-grained sand»tont\ Notwithstanding the piessurc of the steam the water passed through the slab with ease. The appalling outburst at St. Pierre was practically, according to this view, the burst of a subterranean boiler in which the pressure had become too great for the i-iass of rrck above- to resist any longer. — On certain linei of railway it has long been the practice to fill the foot-warmers, not with water, a= i« commonly supposed, but with a saturated solution of sodio acetate, a compound which retains us heat for a longer period. The same principle is reamed now that the foot-warmers are superseded by radiatois placed beneath tho seats of the carnages and heated by a steam pipe from the engine. Each radiator consists of a double iron cylinder, the inner one being filled with the acetate, the annular space between the. two being in connection with the steam-supply. In order that the passengers may have some control over the amount of heat given out. the radiator? are- enclosed in boxes line-d with asbestos, a bad conductor of heat ; and these boxes can be opened or closed by operating a handle within convenient reach of the travellers.

— Science has enabled growers to be independent of seasons and to be able to arrange against emergencies Briefly, the system of refrigeration or retarding the growth of bulbous plants by cold storage may be said to have revolutionised the whole theory and practice of flower culture, and few have- any idea of its development during the past tv/o or three years. Its extent may be judged from the fact that one London firm has rreently erected, at a cost of £30,000, the finest cold-producing machinery and refrigerating chambers- for this purpose in the world. Lying in them at the present moment are upwards of 10,000,000 bulbs of lilies of the valley, which in about 21 or 22 days can bo brought into bloom When the bulbs leave tho cold room they aio left for 24 hours befoie being planted in boxP9 and placed in hot'ioupes, where in four or five days they throw up tall foliage. A few yeai« ago. when the first experiments in this direction were being tried, tiny bunches of «ix or eight epikes realised at Christmas a« much as a guinea, but now it figures practically all the year round as one of the cheapest flowers to be raised and sold

— Electric illumination has so many advantages for domestic purposes that any in\pntion rendering it cheaper or more efficient is a matter of great commercial importance ; this fact lends a good deal of interest to the recently-invented "-CrawfordVoelker" lamp. As far as appearance goes, the new lamp is exactly like tho familiar

"glow-lamp,' consisting like it of a filament enclosed in a glass case, from which the air is extracted. The difference lies in the nature of the filament, which is composed of titanium carbide instead of carbon. The filament is made by baking, in tho electric are, a carbon filament impregnated with an organic compound of titanium The advantage of the new lamp consists in the small expenditure of electric power needed to maintain the light: the energy consumption per candle is- said to be 2£ watts, or, in other words, a one-horbe power dynamo h sufficient to light 19 lamp-, each of 16eaiulle power; this is mm h more economical than any of the carbon filament glow-lamps in use at present. So far the lamp is still in the experimental stage of its history, as one or two slight difficulties in producing it on the commercial Foale are not yet overcome ; but the experiments are so promising as to warrant the expectation that it will soon be on the market. If so. it cannot fail it> render domestic electric lighting cheaper than it is at p repent.