Science Notes.

Freethought Review, Volume I, Issue 4, 1 January 1884, Page 5

Science Notes.

It is not generally known that the spectroscope is used as a weather forecast. If there is an absence of watery vapour lines in the spectrum of skylight, a spell of dry weather may be . predicted ; and vice versa. It would be an interesting addition to a meteorological chart to publish a diagram showing the spectrum of skylight. The British Medical Association appointed some time ago a Collective Investigation Committee. Among the first duties undertaken by this committee was the investigation of the communibility of phthisis, and it has already made considerable progress. Directly affirmative evidence was obtained in 261 returns out of 1078.

One of the latest novelties in explosives takes the shape of blasting paper, which consists of unsized paper coated with a hot mixture of 17 parts yellow prussiate of potash, 10 of charcoal, 35 of refined saltpetre, 70 of potassium chloride, 10 of wheat starch, and 1500 of water. Alter drying, the paper is cut into strips and these are rolled into cartridges. The inventor is Herr Petry of Vienna.

Mr. Rassam, who has been engaged for some time in excavating amongst the ancient ruins of Assyria and Babylonia, has unearthed close on 40,000 inscribed tablets. These were of unbaked clay, and showed signs of crumbling to powder on being exposed to the air, but this difficulty was met by baking them before the atmosphere had time to act injuriously. In this way they have been nearly all saved, and forwarded to England for deciphering.

Two comets are now overdue. The comet of 1812 had, according to Encke's determination, a period of 70J years, and it is now 71 since it was in perihelion. Since Encke's time, however, it has been ascertained that its period will probably be something longer; but, making full allowance for the more recent investigations, the comet should come into view before many months are over. The other comet for whose appearance a watch should now be kept is known as Tempel's second periodical comet. It has a period of a little over five years, and was seen in 1873 and 1878. Tempel's first periodical comet has a period of about a year longer, and was last seen in 1879. Neither of them is conspicuous, but that of 181 should be more sensational. Electricity from light has been accomplished by Sauer's battery, which consists of a glass vessel containing a solution of 15 parts of table salt and seven parts of sulphate of copper in 106 parts of water. Within is a porous cell containing mercury. One electrode is made of platinum, and is put in the mercury ; the other is of sulphide of silver, and is placed in the salt solution. Both are connected with a galvanometer, and the whole is enclosed in a box when not in use. When the battery is placed in the sunlight, the galvanometer needle is deflected to a certain point, and the sulphide of silver is found to be the negative pole. A passing cloud over the sun is indicated by the needle. The action of the battery depends on the effect of the chloride of copper upon the mercury. Sub-chloride is formed, and reduces the sulphide of silver, but this can only take place with the aid of sunlight.

In the August session of " The American Association for the Advancement of Science," Professor E. D. Cope in a lengthy address maintained that the doctrine of the direct descent of organic species from pre-existent species throughout the geologic record is proved and certain. The process is from simplex to complex forms of life. We are approaching a complete genealogy of all existing animals, including man, and facts confirm our belief that however constant species may appear now, they have been at some time variable. Even the structural character of genera, familus, and orders are variable in parts of the system. Man he regarded as developed from a Simian ancestry, although there were gaps yet to be filled. Evolution, he maintained, has proceeded along the line of preferable variation, and the extinction of so many species is due to the fact that they ceased to be beneficial. In the discussion which followed, the majority of speakers upheldthe doctrine of Evolution.

Sir W. Siemens says that the luminosity of burning gases is a secondary phenomenon dependent on the separation and incandescence of solid particles suspended in the flame. Gases from which no such particles are separated,burn with a feebly luminous flame, and this luminosity is assigned to the incandescence of the gases themselves. No experiments have hitherto been made to ascertain whether pure gases heated to a high temperature really emit light. In order to examine this point the author's brother made a series of observations with a Siemens' regenerative oven of the form used in the hard glass manufacture, whereby a temperature of the melting point of steel could easily be obtained. By a suitable contrivance the interior of the oven could be examined, and it was found that, provided the experimental room was kept perfectly still, the heated air in the oven emitted no light. The introduction of a luminous flame into the oven caused its interior to be only feebly illuminated. As a result of the experiments, it follows that the supposition that the luminosity of the flame is due to the incandescence of the gas is incorrect.

It has been noticed of recent years that the four great groups of European Glaciers, the Pyrenees, the Alps, the Caucasus, and the Scandinavian, as well as those of Switzerland and Spitzbergen, have undergone a considerable diminution. It is perhaps difficult to indicate the cause of this retreat, for, from a meteorological point of view, the last few years have not been very different from those which preceded them. Moreover, the advance or retreat of a glacier depends upon several factors ; first of all upon the heat and humidity of the summer, and then upon the frequency and intensity of warm winds. The aqueous vapour of the atmosphere condenses upon the ice, and this water of condensation considerably augments the volume of the water that issues from the glacier. Now, this condensation is accompanied by an evolution of latent heat, which contributes greatly to the melting of the ice. But the extent of a glacier depends not only upon the forces which tend to destroy it, but also upon those which tend to form it, that is to say, upon the accumulation of snow in the basin of reception, which is the origin of the glacier. These snows by degrees become converted into ice, and represent the falls which have taken place during several years. This mass moves slowly, and it is not till the lapse of a great many years that the ice thus formed arrives at the bottom of the glacier, when it melts. All this ice therefore represents the sum of the meteorological actions that have taken place for perhaps more than a century. It would therefore be a mistake to seek in the last few years alone the cause of that retreat of the glaciers which can be demonstrated. This is why the investigation and measurements should be continued ; and the cause of this retreat, if we succeed in ascertaining it, will be an important factor anion" those which engage our attention in the study of the physics of the globe. It would be interesting to know if the glaciers of New Zealand show any appreciable diminution or increase.