No. 112.] 255 



thoughtj upon the construction of an achroniatic g'ass for a mi- 

 crobcope. Not until later days has this important instrument 

 been regarded in its true light ; an instrument of even more value 

 to man than the telescope. The latter is a very inquisitive in- 

 strument, it asks the stars a great many questions, but the stars 

 do not answer ! And the moon too, but we know but little con- 

 cerning her ! So does the microscope,, this little tube we have 

 here, ask questions, but it does not ask them in vain. It will have an 

 answer. It asks most pertinacious questions, and persists and 

 perseveres, until it does get a reply, until it gets the truth, the ihhole 

 truth and nothing hut the truth. Provided you use the microscope 

 and not a microscope. Ihat is, the microscope which is made in 

 imitation of the eye. 



The Prof spoke somewhat in detail of the various instruments 

 constructed by different individuals, concluding that subject by 

 remarking that to say the least, those manufactured by our coun- 

 tryman, Mr. Spencer of Canastota, Madison Co., were equal to the 

 best ia the world. ( This was received with renewed cheers. ) 

 He did not know what principle they were constructed upon, for 

 he had never asked, because he did not wish the secret. It that 

 gentleman had made a discovery by which he could construct 

 glasses, he was entitled to the benefit of that discovery, and he 

 ( Prof. G.) would not wish to know the process for fear he might 

 in an unguarded moment divulge it, and do something detrimen- 

 tal to the interests of the inventor. 



lie then explained the manner of computing the mafinifying 

 power of a microscope ; which is by dividing 8 inches by the focal 

 distance of the glass; supposing the focal distance to be \ of an 

 inch, it magnifies 32 times. 



In considering tlie su'»ject of whicli tlio following lectures 

 are to treat, it will be necessary in the first j)lace to pay attention 

 to the general classificatii'U of insects, and shall do so because, a 

 few days since one of the studmls a^ked me what text books would 

 be necessary, I felt completely bewildered; a large number of 

 works have been written,containing a great deal of valuable infor- 

 mation; I told liini I Would defer a reply then. 1 have since exam- 



