INTRODUCTORY REMARKS. 40 



more especially to the object-glasses of compounds ; eye- 

 pieces not having- been so much attended to of late, unless, 

 indeed, by Professor Airey and Mr Coddington. We must 

 not, however, omit to mention Dr. Goring's plan for con- 

 structing these of corrected lenses; an improvement 

 which has been carried into effect at Vienna. 



A few words may be added on the subject of mounting 

 these instruments for use; a consideration of so much 

 importance, that, if it be not duly regarded, the most, per- 

 fect object-glass will be comparatively of little value. 

 I have seen many simple microscopes on stands so suit- 

 ably formed, that a great deal more might be done with 

 them, than with fme achromatics badly mounted. The 

 necessity of having convenient stands for microscopes 

 seems not to be much attended to, as yet, on the conti- 

 nent, theirs being seldom suited for more than one class 

 of observations. I would not be understood as disre- 

 garding the nicety of their workmanship ; on the contrary, 

 the beautiful finish they give to their productions is 

 hardly to be surpassed by us. As a large portion of this 

 work is devoted to the mechanical part of the microscope, 

 it is unnecessary for me to enlarge upon it here ; I may 

 observe, however, that since the publication of the first 

 edition, considerable attention has been bestowed upon 

 this subject, and that the principles herein laid down are 

 more or less adopted in the construction of all modern 

 instruments. 



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