Periodicity of comets

Periodicity of comets

226 Periodicity of Cornets. [aour. Frank. Irast;, dealbata, which was imported from Australia into India, For fifteen years after its introduction...

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226

Periodicity of Cornets.

[aour. Frank. Irast;,

dealbata, which was imported from Australia into India,

For fifteen years after its introduction it blossomed in October. In 1860 the flowers appeared in September; ten years later in August; in 1878, during the month of July; in 1882, in June. :It therefore reqttired thirty-five years to adapt itself to the climate of India, and to modify its vegetation so that the phases would agree with the seasons of its new home.--Les Mondes, Aug. 4, 1883. C.

MetaUization of Wood.--I~ttbennie]~'s process steeps the wood in a bath of caustic alkali, for two or three days, according to its degree of permeability, at a temperature between 164 ° and 197° F. The wood is then placed in a second bath of hydro-sulphate of calcium, to which is added, aiter 24 or 36 hours, a concentrated solution of sull~lmr. After 48 hours the wood is immersed in a third bath of acetate of lead, at a temperature between 95 ° and 122 ° F., where it remains from 30 to 50 hours. After a complete drying, the wood thus treated is susceptible of a very iine polish, especially if its surface is rubbed with a piece of lead, tin, or zin% and finally finished with a burnisher of gl~ss or porcelain. It then looks like a metallic mirror, and is completely sheltered from all the deteriorating effects of moisture.--Les Mondes, July 28, 1883. C.

0xyeitric Acid.--Edmund Lippmann, a German chemist, has discovered in the incrustations which are deposited in the evaporators during the manufacture of beet sugar, a crystallizable body which is a very energetic tribasie acid. He regards it as identical with the product which has been described by Parvoleck, under the name of oxycitrie aeid.--Les Mondes, July 28, 1883. C. Nervous and I n t e l l e c t u a l C o n t a g i o n . ~ T h e contagion of nervous, intellectual, and moral phenomena, is attracting the attention of French physicians. It comprises nervous tics, epileptiform disorders, insanity and other mental ai~ectlons, the inclination to suicide, crime, etc. M. Rambosson, a ]aureate of the French Institute has published an octavo volume of four hundred pages upon the subject, which was presented to the Academy of M:edicine by Baron Larry, in (~. very complimentary terms.--Les Mondes, July 7, 1883. P e r i o d i c i t y of C o m e t s , ~ P r o f . Zenger has examined the dates of the perihelia of the comets which have been observed since 1.877,

:g~rch, 1884.]

C]toice of a Prime Meridian.

22T

and finds that their successive intervals are multiples of 12'56 idays, o~ one half rotation of the sun. He deduces fi'om this fact inferences which will be of great consequence if they are well sustained. I. The comets are produced by violent explosions, which throw the gases to hundreds of thousands of kilometres from the sun. When this projected matter encounters a cosmic mass the latter will form the nucleus of the comet, and the gaseous material will be the tail. II. The dura-tion of the cometary revolution will be a multiple of the solar half rotation. I f S is the solar rotation, and T the cometary revolution~ we have I t = n__S. 2 The value of n for Euekc's comet is 95; for Brorsen's, 159; for Tempel's, 173.--]~es Mondes, June 15, 1883. C. P h o s p h o r i c G l a s s . ~ T h e phosphoric glass, which Sidot described to the French Academy, resembles ordinary glass in density and refracting power, but it is only slightly affected, if at all, by fluorhydrie acid. Encouraged by the interest which ,was manifested in the Academy, he has continued his experiments, and has submitted a number of retorts, tubes, etc., to the Academy for examination.-Compte.~Ren&ts., June 11, ]883. C. Choice of a P r i m e M e r i d i a n . The Minister of Public Instruction submitted to the French Academy the proposal of the United States government for an international congress, to seiect a universal prime meridian and to agree upon a common standard of time. M. Faye, on behalf of the committee to whom the subject was intrusted, cordially recommended the acceptance of the proposal and the appoini~ment oi' scientific representatives of the various interests, of astronomy, navigation, telegraphy, geography, and terrestrial physics. M. de Chaneourtois proposed a decimal division of the day and of the circumference of the globe, somewhat similar to that which was adopted after the first French Revolution, so as not only to adopt a universal hour but also a universal scale for the absolute measure of time. He thought that the prime meridian should either be that of Ptolemy or that which passes through Behring's straits, both of which would be free from any competition of national pride, since they traverse no habitable lands.--Com2tes ~endus, Jan. 15, 1883. C..