MEMORANDA. 2] 7 



mechanical stage micrometer as the basis of them all ; because 

 it is the means oi proving the accuracy of all the rest. 



Transparent Injections.— I quite agree with your remarks on 

 '^the clumsy width " of the glasses on which these injections 

 (German^ I am told) are mounted (see Journal for last April, 

 p. 131) ; but I should like to be allowed to inform your 

 readers that I have found the said objects remarkably easy to 

 re-mount. One of them (human eyelid) having been acci- 

 dentally fractured, I heated and separated the glasses, and 

 found that the object could be re-mounted, with fresh glass 

 and balsam, as easily as a bee's wing ; which is commonly 

 one of the objects recommended to a young practitioner, when 

 first trying his hand at a " balsam object." 



But, except in case of fracture, or when the original glass 

 is very bad, this process is not needed ; all that is requisite 

 being to slice off, with a glazier's diamond, a piece from each 

 side and end, so as to reduce the glass to the English 

 standard size of three inches by one, and then polish off the 

 edges. 



These trifling operations every microscopist should be able 

 to do ; as he ought to be an illustration of old Ben Frank- 

 lin's definition of a man, viz., " a tool-using animal." I have 

 either cut down or re-mounted eight of these awkward slabs 

 of glass ; and they are now, as you say, " much improved for 

 examination." 



The Astronomer's Protest.— I have been told that I ought not 

 to notice the attack in the April number, p. 133, as the writer 

 shoots from behind a corner ! But I feel it a duty to do so, 

 on account of his depreciation of poor Dr. Goring, to whom 

 we microscopists owe so much, and who he accuses of "ig- 

 norance of astronomy ! " 



A very intimate friend of his, and who is, very righteously, 

 indignant at the derogatory remark, has just written to me 

 that his knowledge of that science was such as to render him 

 well worthy the name of an astronomer. It was a favorite 

 study of his. 



His astronomical apparatus was magnificent, and his largest 

 telescope (a Newtonian of great excellence) was one of the 

 best of the day. So much importance was attached to it that 

 the Astronomer Eoyal went to see it. The Doctor also pub- 

 lished on the subject. 



Among other things he furnished a valuable paper on im- 

 provements in telescopes, to the ' Quarterly Journal of the 



