171 



longitude and declination will be most readily deduced. The for- 

 mula is exemplified by calculations and results of the diurnal varia- 

 tion of magnetic declination for each month at the various Colonial 

 Observatories, and also of the temperature at the Cape, St. Helena, 

 Hobarton, Toronto, Greenwich, Leith, and jMelville Island. The 

 author infers that the temperatures taken at six-hour li/ intervals give 

 for their simifour times the mean temperature of the day, ivhateverhe 

 the commencing hour ; and thus travellers and voyagers observing at 

 5^, 1 1 7^ and 23^, will get the mean temperature of their position at 

 2 P.M. Hence, from the communications of the captains of Merchant- 

 men, the Atlantic oceanic temperatures might be mapped in the 

 course of a year, and the isothermal curves on this broad level sur- 

 face be accurately laid down (see Journ. R. Geograph. Soc. ix. 

 p. 369). Excepting at Mehille Island, is the greatest coefficient, 

 i/zj is nearly constant, and 



sin (J-t \h-^ -\- cos 8 1 cos 2 t (F sin t G cos t^ 

 will give the yearly formula : the homonymous hours are expressed 

 by Hh- Rj sin (it-\-\Pi) as in the oceanic tides nearly. At Melville 

 Island, \p^=45° nearly and Rg is the greatest. The semester from 

 midwinter to midsummer is also nearly expressed by 



P + Qsin O long, for R^. 



Having obtained the empirical R and \p, or A and a, any theoretic 

 formula can be tested by the results. 



April 29, 1852. 

 The EARL OF ROSSE, President, in the Chair. 



The following communications were read : — 



1. Notes on the Impregnation of the Ovum in the Amphibia 

 in a Letter to Thomas Bell, Esq., Sec. R-.S. Communicated by 

 Mr.' Bell. Received April 27, ] 852. 



April 27, 1852. 



My dear Mr. Bell, — During the month of March, now past, and 

 since an abstract of my Second Series of observations " On the Impreg- 

 nation of the Ovum in the Amphibia" has appeared in the Proceed- 

 ings of the Royal Society for June 1851, I have ascertained that 

 the spermatozoa of the Frog are not only brought into contact with 

 the surface of the egg, in fecundation, as already known, but that 

 some of these bodies penetrate into the thick gelatinous envelopes, 

 as stated by Prevost and Dumas ; and further, I have found that in 

 those eggs which are completely fecundated, some spermatozoa have 

 arrived at, and become partially imbedded in the internal envelope 

 which encloses the yelk, although I h.ave not yet been able to detect 

 any within the yelk itself ; nor have obtained any evidence of the 

 existence of an orifice, or natural perforation in the external en- 

 velopes, through which these bodies might enter. 



