fiS6 Letter of Spallanzani to C. SeneUef 



Inunlcate the knowledge he pretended to have of Bacon'ii 

 mventions. A man ignorant of what he professed would 

 never have unnecessarily exposed himself to the danger of 

 being held up by the rival court physicians as an empiric 

 in " perspective" (optics), and consequently, as they would 

 not have failed to infer, in medicine. Thus we have great 

 reason to believe that Dr. Recorde possessed considerable 

 knowledge, at least of the theory, of that combination of 

 optical glasses now called a refractiiig or dioptrical telescope. 

 [To be continued.] 



XLI. Letter of Spallanzani to C. Senebier in regard to 

 Respiration^. 



X ou know that for a long time the respiration of man and 

 of animals has been the principal object of my physical re- 

 searches. I made you acquainted with the motives which 

 induced me to treat on this subject, and the plan which I 

 formed of subjecting to examination the different classes of 

 animals, beginning with those where animality ends, and 

 ascending by degrees to that w^hich comprehends the mam- 

 malia. Before my labour, which is pretty far advanced, be 

 completed, I am desirous of communicating tQ you some 

 parts of it ; but this is not so much to gratify your wishes 

 as to know vour opinion of it. I shall, therefore, take the 

 opportunity of this letter to communicate to you in parti- 

 cular a phienomenon, the enunciation of which will, per- 

 haps, excite in you some surprise. 



As 1 intend to treat on respiration, it is evident that I 

 ought to introduce living animals which breathe. I shall, 

 however, pursue a contrary course, and shall first give my 

 observations on dead animals, or animals which have been 

 deprived of respiration. 



Aninials which breathe have, indeed, been the first object 

 of my researches ; but in proportion as I observed the che- 

 mical changes produced by them in air during their life, I 

 endeavoured also to discover those produced after their 

 death. 



No means certainly can be more efficacious for advan- 

 cing the progress of the physical sciences than to open a new 

 route, or to continue that which has been trod by other phi- 

 losophers, setting oat from the point where they stopped. 



* From the Jciirnal di P'D'sique, Fructidor, an. ii. 



The 



