Illuminating, &c., with High Poivers. By Rev. W.II. Dallinger. 169 



beautifully clear in the part best in focus, and cross lines all over 

 the remaiuder), and Surirella gemma (the dots being sharply 

 separated). These results are not given as extraordinary in them- 

 selves, as I believe they have been accomplished with the same 

 power by ordinary methods. But so far as my own experience is 

 concerned, the ease with which they are secured with this apparatus, 

 is scarcely to be compared. 



I have also found this lamp of great service in the use of that 

 difficult piece of apparatus a vertical illuminator for opaque illu- 

 mination with high powers, the command possessed over the 

 position of the flame tending to give results not otherwise attain- 

 able. This is specially the case when examining dry bacteria or 

 monads opaquely with a -Y^ih. or iVth. 



The same to some extent will apply to the use of the silver 

 side refiedor. The power to dispose of the image of the flame as 

 may be desirable, as easily as the position of the object on the 

 stage of the instrument, greatly facilitates richness of illumination. 



But it will be seen that all but the first result claimed for this 

 piece of apparatus and the method of using it, are more matters of 

 convenience or luxury than anything else. They can be accom- 

 plished without it. But to get the particular central illumination 

 referred to, some such apparatus must be employed ; and the value 

 of that illumination, in minute investigations on organic structures 

 with the highest powers, cannot well he over-estimated. 



The instrument has been beautifully made, first for myself, and 

 then for Dr. Drysdale, by Mr. G. S. Wood, of the firm of (late> 

 Abraham and Co., Liverpool. 



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