279 



80 far as his own observations extend, the trough, or special spawn- 

 ing-bed, is excarated by the female alone, and by means of a pecu- 

 liar action of the tail. The belief hitherto entertained has been, 

 that she was greatly aided in this removal and replacing of the 

 gravel by the snout and under jaw of the male. The process of 

 laying usually occupies three or four days. He found in the course 

 of his experiments, that the death of the female did not (at least 

 within a short time) destroy the vitality of the spawn, or its recep- 

 tive power of fecundation. He impregnated ova from the body of 

 a fish which had been dead for nearly two hours, with the milt of a 

 living parr, and vivification followed in the usual course. 



2. On the use of the word " Temperature" in the Analytical 

 Theory of Heat. By Professor Kelland. 



" It appears to the author, that the only fact established by the 

 experiments of MM. Dulong and Petit is the following :— That 

 the scale of measurement by which we express our knowledge of 

 the state of heat within a body, is not applicable to the expression 

 of the flow of heat within or from the surface of the body. Pro- 

 ceeding upon this supposition, he deduces the thermometric tem- 

 perature of a body, from the formulae in v, given by M. Fourier, 

 taking the formulse as finally obtained, believing them to be accu- 

 rate expressions of physical conditions. As, however, the letter v 

 cannot, consistently with MM. Dulong and Petit's experiments, de- 

 note the thermometric temperature, but some exponential function 

 of it, the author proposes, in order to prevent confusion, to employ 

 the word " thermature" to denote that to which the flow of heat is 

 proportional. Should his view of the matter be correct, investiga- 

 tions, similar to those given by M. Libri and others, in which the 

 external radiation only is supposed to follow the exponential law 

 of temperature, cease to represent physical facts. In order, there- 

 fore, to give an air of probability to the hypothesis, independently 

 of that which it possesses arising out of the nature of the case, the 

 author has tested it by the experiments of MM. Fourier and Biot, 

 and finds that it applies equally well with the old hypothesis, which 

 is confessedly a very close approximation to the truth for small 

 diflFerences of temperature. To complete the test, other experi- 

 ments are wanted, such as those on the state of heat at one end of 

 a short bar, corresponding to a given state of heat at the other. In 

 this case, the old hypothesis totally fails ; but from want of a suflB- 



