ON CONSTRUCTING STANDS OF MICROSCOPES. 153 



their fabric, while they are correctly adapted to their in- 

 tended use, and, therefore, perfect in their kind. The 

 construction which I wish to discover myself, is that of 

 an approximation to a standard for general purposes ; and 

 I think the principles at least of such a structure may be 

 ascertained, though the best possible way of carrying them 

 into effect, perhaps, cannot at present — at least by myself. 

 In the first chapter* I have already sketched an outline 

 of the kind of instrument which I here propose now to 

 fill up and reduce to a determinate form, but shall first 

 detail a few of the obstacles which all who attempt to 

 reform the construction of microscopes may be expected 

 to encounter. First, there is the inveterate hatred and 

 contempt of all innovation whatever, which seems to 

 form a part of our nature, when arrived at a certain 

 period of life. Men long used to some particular way of 

 doing any thing, cannot endure the idea of going to 

 school again, and learning to act upon a new system. 

 The very idea of the possibility of being taught any thing, 

 galls and wounds their self-love to the quick : if this 

 concerns a matter relative to their particular profession, 

 or something, perhaps, on which they peculiarly pique 

 themselves : they become altogether indignant and 

 furious. If by any possibility they arc brought to recog- 

 nise the necessity of some change, they must make it 

 themselves j what a disgraceful and lamentable poverty 



* Chapter VII. in this edition. 



