■■■» 



) 



1 



66 On Microscopes and Microscopy. 



The supply of water from the cistern to the *box A, is cut off 

 by a stop-cock at the cistern, aqd^the water -may be entirely 

 drawn off from the box, by a small cock at J, under the floor. 



It will be perceived that this arrangement is compact and sim- 

 ple. There is no part liable to get out of order, or that once out 

 of order, cannot be easily reached for the purpose of repairs. 



By means of one fire, and that not large, we heat the sand-bath 

 sufficiently, maintain a large water bath constantly at 212° F., 

 make from ten to fifteen gallons of perfectly pure water per day 

 heat a large drying oven, and keep a constant supply of hot water 

 over the sink for washing. Everytning takes care of itself ex- 

 cepting the fire, and the occasional pumping of cold water into 

 the condenser, I am unable, after two months of experience, to 

 suggest any important improvement in these arrangements, and 

 feel confident that any one who should put up a similar apparatus 

 would not be disappointed. 



Prof Porter of Brown University is partially copying after this 

 model for his new laboratory in that institution. 



I must here express my obligations to Mr, Culver, of the firm 

 of Culver & Cory, New Yorki His practical skill enabled me to 

 overcome several difficulties which at first appeared quite formi- 

 dable. Nearly all of the iron and copper work was done in the 

 shop of Messrs. Culver & Cory, and in so substantial and sat- 

 isfactory a manner, that I can safely recommend them to all 

 who may contemplate putting up anything of the kind I have 



described. Having the patterns and the experience, they can 



work cheaper and better than those who have never done any 

 such business. The iron work is all japanned. The glass should 

 be set with a putty made of boiled linseed oil, as that will harden 

 under the heat to which it is exposed ; the common putty made 

 with fish oil remains soft, and the glass is constantly liable to get 

 out of place. 



Art. Vni. — On Microscopes and Microscopy. 



Prof. J. D. Dana — Dear Sir: — I much regret not being able 

 to communicate to you, before now, some facts on microscopes 

 in answer to the inquiries made. But many circurnstances have 

 prevented me, and although this may come at rather a late hour, 

 yet I trust it will prove acceptable since the facts. relate to a sub- 

 ject possessing at this time more than ordinary interest. 



You are aware that lately I have been somewhat in "the mi- 

 croscopic way," and 1 think that you will learn most from me, by 

 allowing me to go over that portion of the ground that bears 



on my personal experience. 



■4- 



■:±:\ 



m 



^ 



