( 239 ) 

 COKKESPONDENCE. 



A " Society's " Microscope Stand. 



To the Editor of the 'Monthly Microscopical Journal. ' 



87, Bold Street, Liverpool, March 27, 1873. 



Sib, — The Eoyal Microscopical Society has on two occasions per- 

 formed a useful service to the whole body of microscopists by the 

 appointment of committees to investigate questions of general interest. 

 The last (I think) resulted in the adoption of the universal screw for 

 the attachment of object-glasses. 



I beg to suggest another investigation, which, I think, would bo 

 well worthy of the Society, and which no other body could so well 

 perform. It is, that the Society should appoint a committee to ascer- 

 tain and recommend the best form of stands' tor microscopes. 



Two forms are in general use, one in which the compound body 

 slides in a groove in a fixed bar, the other in which the compound 

 body is held at the lower end by a transverse bar, which is again 

 attached at right angles to another bar, the whole of these being 

 moved in order to focus the object, except when the fine adjustment 

 suffices. The fitting and position of the fine adjustment necessarily 

 differs in these two forms. 



Many instruments in which the optical parts are the best which 

 have been constructed, exhibit, when used with high powers, a tremor 

 which greatly impairs definition, and which, I believe, to be due — not 

 to the imperfection of the workmanship, nor to unavoidable defects — 

 but to a faulty model. 



The subject has become increasingly important since the more 

 general introduction of high powers, and their use in rooms where 

 numbers of persons are assembled. 



I am, Sir, your obedient servant, 



John Abraham, 



President of the Liverpool Microscopical Society. 



The Battle of the Glasses. 



To the Editor of the ' Monthly Microscopical Journal.'' 



Cincinnati, Ohio, April 1, 1873. 

 Sir, — Two weeks of convalescence have given me time and oppor- 

 tunity to become interested in the " Battle of the Glasses " ; and the 

 March number of the ' M. M. J.' coming opportunely to hand, I con- 

 cluded to try what I could do towards reproducing the appearances 

 of Lepisma saccliarina, figured in that number, Plate XI., by Mr. 

 Hollich, for Dr. Pigott. Beginning with a Tolles' Jth, 1868, ang. ap., 

 150° dry, first with the B eye-piece, and then with Tolles' solid eye- 

 piece, the appearance of Fig. 1 was easily produced ; and then rotating 

 the stage, so as to put the scale in the position shown in Figs. 2, 3, and 

 4, Plate XI., there was little more difficulty in producing appearances 



