139 



sixteen species of Coluber, and three of the genus Boa, which have 

 these lateral orifices ; that they have not as yet been discovered in 

 the genus Anguis ; and that in general it appears that only venomous 

 snakes have this distinctive character. 



From Mr. Home's description and remarks, we learn that these 

 orifices do not lead to the nostril or to the ear, but to a distinct bag 

 of a rounded form, there being within the skull a hollow of the same 

 shape, surrounded by bone, which seems purely intended to receive 

 it. This cavity is described as resembling a cup, formed by the bones 

 of the skull and those of the upper jaw, and not unlike the orbit. 

 The bags bear a relative proportion to the size of the snake ; they are, 

 like the eyelids, lined with a cuticle, which forms the transparent 

 cornea, making a part of the outer cuticle ; both which, it seems, are 

 shed at the same time. 



Mr. Home proceeds next to a description of similar bags in the 

 deer and antelope kinds, which were by some thought to be lachry- 

 mal glands or ducts. On close examination, however, it is found 

 that these bags have a secretion of their own, and that there is no 

 reason for thinking that tears ever pass into them, the passage into 

 the nose being unusually free, and the orifices of the bags in general 

 unfavourably situated for the reception of the tears. The use to 

 which the fluid secreted in these bags is applied, is as yet unknown. 

 In the snake this apparatus has that position which seems best adapted 

 to pour out the fluid upon the cornea when the head of the snake is 

 in an erect position. 



An Enquiry concerning the Nature of Heat, and the Mode of its Com- 

 munication. By Benjamin Count of Rumford, V.P.R.S. Foreign 

 Associate of the National Institute of France, $c. Read February 

 2, 1804. [Phil. Trans. 1804, p. 77.] 



The importance of the investigation here entered into, inasmuch 

 as it applies to most of the operations of nature as well as art, ap- 

 pears so manifest, that we shall not recapitulate what the author ad- 

 vances on that subject. Before he proceeds to the detail of his ex- 

 periments for the purpose of computing the emissions of heat from 

 various bodies under a variety of circumstances, he finds it necessary 

 to premise a minute description of the principal part of the apparatus 

 he contrived for his purpose. This instrument consists of a hollow 

 cylindrical vessel of brass, four inches long, and as many in diameter. 

 It is closed at both ends ; but has at one end a cylindrical neck about 

 eight-tenths of an inch in diameter, by which it is occasionally filled 

 with water of different temperatures, and through which also a ther- 

 mometer, constructed for the purpose, is occasionally introduced, in 

 order to ascertain the changes of temperature in the fluid. As it was 

 in the first instance only meant to observe the quantity of heat that 

 escapes through the sides of the vessel, two boxes were contrived, 

 filled and covered with non-conducting substances, such as eider- 

 down, fur, &c., which were fitted to the two ends or flat surfaces of 



