On the Periodic Change of Climate caused by the Moon. 433 



the thermometer being fixed in the tubulure by a divided cork 

 in the manner above described. The heat may be urged until 

 the retort commences to soften. 



In the distillation of coal-tar I have observed that towards 

 450° this substance intumesces, slowly evolves hydrogen, and is 

 changed into carbonaceous matter. At this temperature the 

 greater number of organic compounds, even of the most stable 

 constitution, commence to decompose. 



The boiling-points of bodies but slightly volatile may be in 

 this way easily determined. I have ascertained, for example, 

 that retene, C 36 H 18 , boils at 390°, and that perchlorinated naph- 

 thalene, C 20 C1 8 (prepared by means of antimony chloride), boils 

 at 403°. I have also found that the boiling-point of sulphur re- 

 mains constant during the entire process of its distillation. 



The thermometer as above described was made by M. Alverg- 

 niat, Passage Sorbonne, with his well-known skill. Its form is 

 that of a thermometer to be used in fractional distillation. But 

 it is clear that the reservoir B and the anterior portions of the 

 capillary tube may possess any direction required by the nature 

 of the operation in which the instrument is intended to be em- 

 ployed. 



L. On the Periodic Change of Climate caused by the Moon. By 

 Charles V. Zenger, Professor of Natural Philosophy at the 

 Polytechnic School at Prague*. 



IT is now generally admitted by meteorologists that the influ- 

 ence of the moon on atmospheric pressure and temperature 

 is scarcely appreciable, if computed by means of short periods, as 

 those of its synodical revolutions. The rapid motion of the nodes 

 and of the apsides produces a constant and periodic change of 

 positions from one synodical revolution to another ; yet no refer- 

 ence to it is made in researches instituted for the purpose of ac- 

 counting for the lunar influence on climate. The investigations 

 of MM. Schiibler, Kreil, and Buys de Ballot on that interest- 

 ing object, though partially based on a large series of observa- 

 tions, have failed to ascertain the lunar influence in question. 



Yet the object seems to merit that new attempts should be made, 

 seeking a solution in other ways and by other means than formerly 

 were used. Success seems to me to depend on finding out the 

 true period of lunar influence ; and that is only possible by com- 

 puting a large series of observations carefully made at short in- 

 tervals with apparatus well adjusted and placed at a constant 

 height above the ground. I therefore resolved to calculate the 

 observations of the Meteorological Observatory of Prague, made 

 from 1840 till 1 866, hourly, by means of self-registering apparatus. 

 * Communicated by the Author. 



