280 



Lieut. Elagin's Determinations of the Dip. [Feb. 11, 



part of the Ichthyic and Batrachian bone ; but just as this coalescence 

 begins, ossification proceeds inwards from these " parostoses," and affects 

 the overlying cartilage, the cartilage of the basisphenoidal region having no 

 other osseous nuclei. This process of the extension inwards of ossification 

 from a splint-bone to a cartilaginous rod or plate I have already called 

 " osseous grafting"*. 



In my former paper the basisphenoidal " rostrum " and " basitempo- 

 rals " were classed with the endoskeletal bones ; they will in the present 

 paper be placed in the parosteal category, in accordance with their primor- 

 dial condition. 



By the careful following out of these and numerous other details I have 

 corrected and added to my previous knowledge of the early morphological 

 conditions of the Bird's cranium, and at the same time, I trust, have con- 

 tributed to an enlarged and more accurate conception of the history and 

 meaning of the Vertebrate skull in general. 



II. "Determinations of the Dip at some of the principal Obser- 

 vatories in Europe by the use of an instrument borrowed from 

 Kew Observatory." By Lieut. Elagin, Imperial Russian Navy. 

 Communicated by Balfour Stewart, LL.D. Received February 

 2, 1869. 



Before I give a short account of the observations and the results de- 

 duced from them, I beg to express in the first place my best thanks to Dr. 

 Balfour Stewart, Director of the Kew Observatory, who, having heard of 

 my desire to take the dip at different places, was so kind as to lend me an 

 instrument from the Kew Observatory, — also to James Glaisher, Esq., 

 F.R.S., &c, who furnished me with a tripod- stand, which I found to be of 

 great use to me on some stations. 



I may also remark that, having other duties to perform in obedience to 

 instructions from the Russian Government, I could only devote a portion 

 of my time to the observations of dip. 



The instrument I had from Kew Observatory was one of Barrow's Dip- 

 Circles, furnished with two 3|-inch needles in the form generally used at 

 the Observatory. The Dip-Circle used had been in use for some time at 

 the Kew Observatory, until, it having been ascertained that one of its needles 

 was somewhat deteriorated, it was replaced with that now in use. 



Before I left Kew Observatory I was aware that one of the needles was 

 not as good as might be desired ; but as Mr. Stewart bad no other circle 

 suitable for my purpose, I considered it desirable to take this circle. 



The observations were made according to the instructions of Lieut. - 

 General Sabine, given in the f Admiralty Manual of Scientific Enquiry/ 



The following Table I. shows the results of the observations with the 

 circle from Kew ; in it the name of station and the date of observation are 



* See memoir « On the Shoulder-girdle and Sternum," Ray Soc. 1868, p. 10. 



