1814.] Wernerian Society. Imperial Institute. 71 



alter its economy. After keeping it some time, the five legs began 

 to sprout out, but they only attained half the length of the old 

 ones, and were not therefore of much use. But they enabled it to 

 spin a web on which it usually sat. Every time the animal cast its 

 skin the feet became longer. 



The Society adjourned till the first of November. 



WKRNERIAN SOCIETY. 



At the meeting on the 16th of April, the Secretary read a com- 

 munication from the Rev. Dr. Fleming, on the species of mus 

 found in Scotland. The original genus mus has been subdivided 

 into several genera, myorus, arvicula, and mus. The first genus 

 includes only the dormouse, which was observed in Scotland by 

 the late Dr. Walker, but is rare. Of the genus arvicola, Mr. 

 Fleming mentioned three species, agreslis, terresiris, and amphi- 

 lius. Of the restricted genus, mus, he enumerated six species, 

 viz: the common mouse; the field mouse; the harvest mouse; 

 the black rat, M. rattus ; the brown or Norway rat, M. decu- 

 manus ; and the mus qiger, which Mr. Fleming procured in Lin- 

 lithgowshire, and which he considers as a species hitherto non- 

 descript. 



At the same meeting, the Secretary read a communication from 

 Mr. \V. Bullock, giving an account of some rare birds observed by 

 him among the Orkney islands, in the summer of 1812. He 

 found in Hoy all the four species of eagle, generally accounted 

 British, viz : the golden, the ancreous, the ring-tailed, and the 

 sea eagle. In North Ronaldsha he observed the large snowy 

 owl ; arid near Passa Westra the great auk. The first of these had 

 not before been ascertained to be British ; the latter has scarcely 

 been seen on our shores for the last 50 years. Specimens of both 

 are now preserved in his museum. 



IMPERIAL INSTITUTE OK FRANCIS. 



Account of the Labours of the Class of Mathematical and Physical 

 Sciences of the Imperial Institute of trance during the Year 1813. 



(Continued from vol. iii. p. 4(57.) 



A portable Barometer of a new Construction. By M. Gay- 

 Lussac. 



This is a syphon barometer. What distinguishes it from every 

 other known at present, is that it has neither stop-cock, screw, nor 

 piston. The shorter branch is shut at its extremity ;. but two or 

 three centimetres below this extremity there is a capillary hole, 

 ■efficient for the lice admission of the air, but too small to allow 

 the mercury to escape, even when it passes over the opening. 



This branch is united to the larger branch of the syphon by a 

 tube, the interior diameter of which is about a millimetre, and its 

 length above the curvature two or three decimetre*. This disposi- 

 tion has tin advantage, that if air enters into the curvature of the 

 baiomcter during the carriage, the mi nury will expel it when the 



