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No. 10 a immersion, is a glass which in its working power is 

 considerably better than the English -jirth., and has the great 

 advantage of admitting of the nse of covering glass of some 

 thickness, besides giving ample light. We make this state- 

 ment after careful comparison in various kinds of Avork with 

 the best English glasses, and. with the assistance of experienced 

 manipulators. This glass costs eight pounds, whereas for its 

 equivalent in this country we should certainly pay twice that 

 sum. Microscopists, and especially young students who have 

 not money to throw away, should remember this ; and most 

 confidently can we assure them that they may rely on Dr. 

 Hartnack's work. Still more remarkable is the difference 

 between the prices of the dry French glasses and the equi- 

 valent glasses of English makers. We possess a No. 8 of M. 

 Verick (nearly the same as Dr. Hartnack's No. 8), which, 

 after careful comparison with first-rate English glasses, we 

 consider most satisfactory in performance. A very celebrated 

 English microscopist — who should know better than any man 

 the value of a high power — declared to us after comparison, 

 that this No. 8, which cost two pounds, was quite as good 

 a glass as his iVth, which cost eleven guineas. Well, these 

 are facts for the consideration of English students, especially 

 of those who are thinking of buying microscopies or high 

 powers. We strongly advise them to purchase the foreign 

 glasses, and to thus induce the English makers to offer their 

 work at a reasonable price. The main cause of the great 

 difference of price is, we believe, in the difficulty of working 

 Lister's system, Avhich is that to which the English makers 

 adhere ; but English prejudice and a close market have more 

 to do with it. In the matter of distance between cover-glass 

 and lens, and amount of light, the foreign glasses have a clear 

 advantage over English ones, independent of price. 



Another subject, which is of the same nature, is the relative 

 value of the English and foreign microscopes themselves. We 

 protest against the long-tubed, many-wheeled, awkward Eng- 

 lish model, and much i^refer for ivork the small French body. 

 It is a great deal cheaper, which is one important thing for 

 the student. One English maker has recently brought out 

 a quite small microscope-body, which we should highly ap- 

 prove with one or two alterations. Such a body with a 

 French No. 4, and 8, or Nos. 3, 6, and 8, should not cost 

 the student more than six guineas or seven, and would be 

 actually a first-class instrument. 



We may here add one Avord as to the No. 15 (immersion) 

 of Hartnack — a glass equivalent to a -^Vrd on the English 

 scheme — and of which as yet not more than six have been 



VOL. X. NEAV SER. U 



