[ xliv ] 



verance, and clofe attention were 

 requifite, I deferred the undertak- 

 ing till 1 fhould find myfelf more 

 fit for it, 



Detached experiments may in- 

 deed be very ufeful when a fuf- 

 ficient number is collected to draw 

 fome conciuflons from them ; but, 

 without purfuing methodically the 

 fame object, difcoveiies are to be 

 expected only by mere chance, 

 and are even fometimes overlooked, 

 I owe to the example of my worthy 

 friend, the Abbe Fontana, the tho- 

 rough perfuafion, which I now en- 

 tertain, that natural knowledge can 

 make but a very flow progrefs in 

 the hands of thole who have not 

 patience and affiduity enough in 

 purfuing one and the fame object, 

 till the v difcover fome things un- 

 difcovered before ; or till they fin<3 



