58 DR. PAYNE. 



English or foreigtij are the best. It is usual to furnish 

 students' microscopes with nothing beyond a l-4th, but we 

 quite agree with Prof. Michael Foster's opinion, expressed in 

 his ' Report on Modern Microscopes/ that it is very desirable 

 for students, if possible, to have something higlier. The 

 extra expense of a -^th, or even an -^^th, is not thrown away. 

 As to the description of glass, there can be no question as to 

 the excellence of the objectives made by the great English 

 makers, whom we need not name, but their workmanship is 

 rather expensive. With the exception of the latter point, the 

 same may be said of the best French object-glasses, such as 

 those of Hartnack. They are decidedly cheap, and yet it 

 would be difficult or impossible to find any inferiority in their 

 optical performance, as compared with that of the best and 

 most costly English glasses of corresponding power. They 

 have, however, two or three practical inconveniences. In 

 the first place, the distance of the lens from the object is 

 in the higher powers (from -^ih upwards) inconveniently 

 small ; and, in the second place, none but the immersion 

 lenses are usually furnished with a correction for thickness 

 of covering glass. We have separated Plartnack from other 

 Continental makers, and this is partly on account of his 

 incontestable reputation, partly because we can speak of his 

 instruments from personal knowledge, but it should be said 

 that many good judges place some other French and German 

 glasses in the same rank, and we do not wish even to 

 suggest that others may not be equally good. At the same 

 time, judging from some of the specimens sold in London 

 with the names of noted Berlin makers, the workmanship of 

 the latter cannot be so uniform. Regarded as a matter of 

 econony, then, the best foreign glasses are a good invest- 

 ment ; but so many inferior glasses are imported, especially 

 from Germany, that German high powers should, if possible, 

 not be bought, otherwise than from the makers, without trial 

 or examination or else a guarantee. The same precautions 

 are, however, much to be recommended in purchasing any 

 objective whatever. The question of object-glasses does not 

 stand quite alone, for, though the different parts of the instru- 

 ment may be obtained from different makers, it is generally 

 expected that some objectives, at least, w^ill be taken with a 

 stand, and some makers will not sell separate objectives except 

 at an increased price. 



Now, as to the relative advantages of English and foreign 

 microscopes, taken as a whole, we do not pretend to express 

 an opinion, but we may state some of the reasons urged on 

 both sides. In favour of an English microscope it is said that 



