The Microscope. 217 



please fasten them immovably? The microscopist is now on 

 his vacation, and he is tired by the year's work ; he does not care 

 to add to the weariness of his fingers by continually pushing the 

 clips back into place ; neither does he want them to glide around 

 slowly and then with a screech of fiendish glee snatch off the 

 cover glass and crunch it up. He is in the quiet woods or by 

 the murmuring sea, and in neither place does he want to frighten 

 the birds or the fishes by saying bad words. So please fasten 

 those clips; and do not make them needlessly stifi^. 



A simple disk diaphragm will be needed, but it should be so 

 arranged that it can be entirely removed, as this ideal stand will 

 have a substage ring to receive the condenser. This ring should 

 be so large that it will take any modification of the Abbe con- 

 denser in the market, an adapter being the portion of any that 

 shall not properly fit. See that the ring is large enough, and 

 also that it is so attached that it can focus the condenser by being 

 slid into position by the fingers. 



The concave and plane mirrors will be so arranged and 

 mounted that the whole may be removed and placed in the 

 proper position on the upper surface of the stage to illuminate 

 •opaque objects. Its curvature should therefore be such that it 

 will be focussed on the object when it is attached to the stage. 



That is all. The ideal travelling stand, therefore, is only a 

 kind of skeleton affair without eye-pieces and without objectives, 

 because the purchaser will have these on his larger home instru- 

 ment. It will be as simple and as cheap as is possible with good 

 workmanship and good service. 



The optician that undertakes to make such a desirable stand 

 must not forget that his success will depend entirely on the cost 

 -of the instrument. The microscopist already has a microscope. 

 It is too large and cumbersome to be taken with him on his sum- 

 mer vacation. Although he may possess a continental instru- 

 ment, smuggled into the country through some accommodating 

 college, he will find it too heavy to be packed in his trunk or 

 his satchel. In the trunk it may wabble about and damage the 

 bonnets and the — that is to say, the continual jarring may injure 

 it. In his own satchel it soon becomes too weighty to be endured. 

 The continental stand will not answer the purpose. Mr Zent- 

 mayer's Pocket Stand is well named, for it is light enough to be 

 •easily borne in the pocket where I have seen it carried. The 



