535 



consisting of two layers corresponding with those usually termed 

 decidua vera and reflexa, was found in the tube, adhering to its inner 

 surface and surrounding the placenta and villi of the chorion. The 

 following is the description given by the author of the appearances 

 observed in the last of these cases : "The uterus was enlarged, and 

 the whole lining membrane coated with a thick irregular layer of a 

 substance resembling the fibrine of the blood, of a red colour, in the 

 upper part. The right Fallopian tube about the middle was as large 

 as a walnut, or larger where its coats had burst, and a coagulum of 

 blood was hanging through the irregular aperture. The tube was 

 pervious from the corpus fimbriatum to the dilated part. On cutting 

 open this expanded portion, a small embryo enclosed in the amnion 

 was observed, and the vesicula umbilicalis, remarkably large, with its 

 peduncle, came into view. All the cells of the placenta and villi of the 

 chorion were seen distended with coagulated blood and surrounded 

 with a deciduous membrane, a great part of which has been separated 

 from the inner surface of the tube." 



XVI. " Experimental Researches on the Conductive Powers of 

 various Substances, with the application of the Results to 

 the Problem of Terrestrial Temperature." By WILLIAM 

 HOPKINS, Esq., M.A., F.R.S., of St. Peter's College, 

 Cambridge. Received June 10, 1857. 



(Abstract.) 



1 , The author remarks, that in giving an account of these experi- 

 mental researches, it is first necessary to define strictly the manner in 

 which the conductivity or conducting power of a substance with 

 reference to heat, is accurately measured. For this purpose, conceive 

 the conducting substance to be bounded by two parallel plane sur- 

 faces of indefinite extent, the distance between them being h. 

 Suppose one of these bounding surfaces (which, for convenience, 

 may be called the lower one) to be kept at a uniform and constant 

 temperature t t ; let the temperature of the upper surface be also 

 constant and uniform, and equal to 2 ; and let r denote the tempe- 

 rature of the free space into which the heat radiates from the upper 



