250 



Dr. Davy on the Congelation of Animak. 



adopting the Kew metliods of magnetic investigation. The completeness 

 of the photographic process is shown by the fact^ that of 1/5,344 hourly 

 positions which should have been recorded in the interval under notice, 

 there were only 1497 failures from all causes whatsoever; and even of 

 these few a considerable portion is shown to be due to the employment of 

 the instruments in other experimental investigations. The paper contains 

 a full statement of the processes of tabulation from the photograms, and 

 of the different stages of reduction through which the tabular results 

 were passed, for the purpose of deriving from them the facts connected 

 with the lunar influence on the terrestrial magnetic elements. A lunar- 

 diurnal variation is shown to exist in each of these elements, — of very 

 small amount, but ha^-ing peculiar and well-marked systematic charac- 

 teristics. It is further shown that these characteristics present a similarity 

 and accordance, which it is impossible to regard as accidental, with the 

 results obtained at several other and widety-separated localities in the 

 middle latitudes of both hemispheres, as for example at Hobarton, Toronto, 

 Philadelphia, Pekin, and the Cape of Good Hope. A magnetic variation 

 shown to be thus obviously dependent upon the moon's position relatively 

 to the terrestrial meridian, and agreeing in its principal features in such 

 various localities, is urged by the author as being ascribable with great 

 probability to the direct magnetic action of the moon, made sensible at the 

 surface of the earth through the production of phenomena which, in the 

 present state of our knowledge as regards the magnetism both of the earth 

 and of the moon, it is as yet difficult wholl}^ to explain, but which are likely 

 to lead to a considerable advance of our knowledge in both these respects. 



The further prosecution of the investigation, both at Kew and else- 

 where, is recommended as highly deserving the attention of those who 

 occupy themselves in the pursuits of inductive philosophy. 



Communications received since the end of the session. 



I. On the CoDgelatioii of Animals." By John Davy^ M.D., 

 F.R.S., &c. Received July 19, 1866. 



In a very interesting and elaborate paper by M. Puget, entitled " Sur 

 la Congelation des Animaux," pubhshed in the * Journal del'Anatomie et 

 de la Physiologic,' the Number for January and February of this year, he 

 refers to a statement of mine, made many years ago*, that the leech may 

 be. frozen without loss of life. The experiments which he has instituted, 

 and which appear to have been conducted with great care, have led him to 

 an opposite conclusion, viz. that congelation is not only fatal to the leech, 

 but to animals generally, without a single exception. He considers the 

 cause of death, the vera causa, to use his own words, to be an altered con- 

 dition of the blood. In consequence of this statement, I thought it right 

 * Eesearches, Physiol, and Anat. ii. p. 121. 



