1048 



S DM MARY OF CURRENT RESEARCHES RELATING TO 



constructed of silver. These drawings are reproduced in figs. 213 and 

 214 ; but they do not givo at all a clear idea of the construction of the 

 instruments. It was thercforo with much interest that we learnt 

 that Prof. A. W. Hiibrecht, of Utrecht, the eminent zoologist, was 

 coming to London, bringing one of Leeuwenhoek's Microscopes, 

 belonging to the Zoological Laboratory of the University of Utrecht. 

 Unfortunately Prof. Hiibrecht' s visit was during the recess, so that 

 there was no opportunity of exhibiting it to the Society, but by his 

 courtesy we were enabled to make careful drawings and models of the 

 instrument, the two sides of which are accurately shown in figs. 215 

 and 216, full size. 



The lens is bi-convex, of about 1/4 in. focus, and is mounted 

 between two concavities, provided with minute apertures, made in two 

 corresponding thin plates of brass, which are held together by three 



Fig. 215. 



rivets, two at the upper end, and one at the lower. The object is 

 held in front of the lens on the point of a short rod, the other end of 

 which screws into a small block or stage of brass, which is riveted 

 somewhat loosely on the smoothed cylindrical end of a long coarse- 

 threaded screw, acting through a socket angle-piece attached behind 

 the lower end of the plates by a small thumb-screw. The long screw 

 serves to adjust the object in the axis of the lens in the vertical 

 direction, whilst the pivoting of tho socket angle-piece on its thumb- 

 screw gives lateral motion. The object-carrier can be turned on its 

 axis, as required, by screwing the rod into the stage. For focusing, a 



