1883.] 



MICROSCOPICAL JOURNAL. 



127 



brass spring compressor, or else by 

 laying a heavy leaden bullet on the 

 cover-glass. After a while it will be 

 found that the shellac holds the cover 

 securely. Then put on one or two 

 more coats of shellac, and when these 

 are hardened finish the slide with as- 

 phalt varnish. 



To produce the multiple images re- 

 quires a little patience. The best 

 eyes for the purpose are those of a 

 large beetle ; but many other objects 

 besides eyes will also give miniature 

 images in the same way. Place the 

 slide upon the stage in the usual way, 

 and focus upon it. Now, it will be 

 understood that any image that may be 

 formed bv the eye will be a short dis- 

 tance above the eye, so withdraw the 

 objective until the eye is slightly out 

 of focus and it will be approximately 

 focussed upon the plane of the im- 

 ages. 



The object to be miniatured may 

 be either transparent or opaque. As 

 transparent objects are most easily 

 managed, it is advisable to begin with 

 them. Select any object that may 

 seem suitable, for example, a small 

 mounted insect, or a transparent pho- 

 tograph, such as is to be found in 

 almost every cabinet. The Lord's 

 Prayer can be read in each one of 

 the single eyes if the proper adjust- 

 ments are made, or a comic picture 

 can be shown there. Whatever ob- 

 ject is selected, place it somewhere 

 between the mirror and the stage, and 

 and throw the light through it to il- 

 luminate the object on the stage. 

 The light must be strong and proper- 

 ly directed, and the distance of the 

 transparent object from the stage 

 must be adjusted for the best effect. 

 Focus the objective upon the images 

 of the object formed by the eye, not 

 upon the eye itself. 



It would be useless to give more 

 detailed instructions than we have 

 given above. It is not an easy mat- 

 ter to get the best effects until one 

 has some practice, — then it becomes 

 a very simple matter. 



To miniature opaque objects in this 



way is much more difficult, because of 

 the strong light required. A favorite 

 object with some persons is the mov- 

 ing second-hand of a watch, which 

 can be shown very beautifully. For 

 this purpose the face of the watch 

 must be covered with dead black 

 paper, leaving only the dial of the 

 second-hand exposed. The second- 

 hand itself should be large and black 

 to be seen well. The watch must 

 now be substituted for the mirror of 

 the microscope, the second-hand be- 

 ing in line with the optical axis of the 

 tube. 



If a strong light is now condensed 

 upon the second-hand by means of 

 two bull's-eye condensers, it will, 

 when properly adjusted, show clearly 

 in each facet of the beetle's eye. 



We propose to say a few words 

 about crystals here, mainly to direct 

 attention to the ease with which they 

 may be prepared as beautiful objects 

 for the polariscope. The subject is 

 too large to be treated at considerable 

 length in this place. Perhaps the 

 few remarks that may be made will 

 bring forth some inquiries concerning 

 points not touched upon in this arti- 

 cle, in which case we shall be most 

 pleased to answer to the best of our 

 ability. 



It is always a beautiful sight to 

 watch crystals forming under the mi- 

 croscope, and with the polariscope and 

 selenite plate, the effect is still finer. 

 Almost any of the readily crystallizable 

 compounds will do for these experi- 

 ments. Bichromate of potash is 

 good without the polariscope, borax, 

 sal-ammoniac, tartaric acid, etc., give 

 fine effects with it, but among the al- 

 kaloids, the salts of quinia, are noted 

 for their fine crystals for the polari- 

 scope. Santonine and salicine dis- 

 solved in alcohol or chloroform and al- 

 lowed to crystallize on the slide, pro- 

 duce beautiful effects. All these may 

 be made to crystallize while we look 

 at them, but the best effects can only 

 be obtained by experimenting with 

 solutions of varying strength. 



For permanent slides, select only 



