same time, that, preliminary to a searching investigation into the 

 qualities of substances for the practical purposes of quarantine, 

 certain points of the first importance, at present unsettled, ought 

 to bo determined in limine, — as whether the plague be truly con- 

 tagious or merely an epidemic disease ; whether it is even endemic, 

 independent of contagion ; and whether, if arising from local cir- 

 cumstances, it is capable of becoming contagious. He remarks 

 how the quarantine system has been unfortunately established on a 

 basis of suppositions rather than on well ascertained facts, and how, 

 consequently, it is held by all those who have given it their 

 careful attention, to be, as a sanatary system, most unsatisfactory, 

 troublesome, expensive, and insecure. He concludes with the ex- 

 pression of the hope that the time is not far distant when a thorough 

 inquiry into the subject will be demanded preliminary to a revision 

 of the quarantine laws, should the results of that inquiry bo that 

 plague is a contagious disease, or capable of becoming so. lu the 

 form of an appendix, he relates some particular instances in illustra- 

 tion of his remarks on the quarantine classification of substances, 

 shewing how the distinctions are acted on practically, and how they 

 tend to vitiate the present system of quarantine, supposing it to bo 

 otherwise perfect. 



3. Results of Experiments on the Specific Heat of Certain 

 Rocks. By M. Regnault of Paris. Communicated by the 

 Secretary. 



Professor Forbes observed that, in his communication to the Royal 

 Society on the Conductivity of Soils for Heat, on the 20th December 

 last (see Proceedings, page 343*), he had referred to the separation 

 of the conductivity and specific heat, which are involved in the re- 

 sults of the thermometric experiments on subterranean tempera- 

 ture. In order to eliminate the effect of specific heat, M, Regnault 

 of Paris (well known by his experiments on this subject) undertook, 

 at the request of M. Elie do Beaumont, to ascertain the specific 

 heats of the soils in which the different sets of thermometers are 

 sunk. These are communicated in a letter from M. E. de Beau- 

 mont to Professor Forbes, as follows : 



Specific Heat. 

 Porphyry of the Cnlton Hill, .... 0.206.i4 

 Another experiment, .... 0.20587 



Mean, 0.20(520 



