i 885.J 



MlCKOSCUriCAL JOUliNAL. 



205 



to rotate upon a pivpt passing through 

 its centre in such a wa}- t^iat the ob- 

 jects are brought successively into 

 the field of the microscope. 



The manner of support of this 

 pivot and its attachment to the stage 

 of the microscope must depend upon 

 the instrument used, which, however, 

 should have a stage with mechanical 

 movements, and the attachment be 

 made to the upper stage-plate, thus 

 giving control of each object when 

 brought to the field, in the same man- 

 ner as if it were mounted upon the 

 ordinary slide. The writer, having 

 a Beck's first-class stand, constructed 

 a pivot support out of a piece of thin 

 board (cigar-box) . two inches wide 

 and three inches long, the pivot be- 

 ing a common wood-screw inserted 

 near one end, and carrying a wooden 

 nut to steady the revolving plate, and 

 the attachment to the stage-plate be- 

 ing effected by means of four small 

 screws driven nearly ho.ne on the 

 under side of the thin strip bearing 

 the pivot, the heads of the screws 

 being so arranged that they slide into 

 grooves on the stage-plate, which or- 

 dinarily carry one of the clamps for 

 securing the object slip, A more 

 elegant, but not more efficient, sup- 

 port of brass has since been obtained 

 of the instrument maker. 



Shallow notches made with a 

 round file on the edge of the revolv- 

 ing plate, into which drops the 

 curved end of a light spring serve to 

 inform the observer when the object 

 is in the proper position in the field. 

 The space within the circle of object 

 is utilized for labelling the specimens. 



Though requiring much verbiage 

 tor a description which may still 

 •-cem not very clear, the apparatus is 

 really very simple, and was entirely 

 constructed by the writer out of ma- 

 terials at hand. Designed solely for 

 the purpose mentioned — the exhibi- 

 tion of foraminifera — yet with slight 

 modifications it seems capable of 

 serving a more general purpose. 

 Transparent objects might be mount- 

 ed on small squares of glass, made 



transferable from wooden or glass 

 slips to the revolving plate as above, 

 the necessary holes being made in 

 the plate to allow the passage of 

 light from below. 



The convenience of such an ar- 

 rangement is obvious, whether for 

 exhibition of objects to the unskilled 

 (the only manipulative skill required 

 on the part of the observer being ad- 

 justment of focus) , or for personal 

 reference and comparison, a series of 

 specimens being examined in this 

 way as readily as if they were plates 

 in a bound volume. 



U.S. Fish Commission Steamer 

 Albatross, 



July 30th. 1885. 



JBauscJi a Loiiib Microtome. 



A short time ago we had an op- 

 portunity to examine and use one of 

 the microtomes recently introduced 

 by the Bausch & Lomb Company. 

 The results of our short trial were 

 eminently satisfactory, and we take 

 pleasure in presenting our readers 

 with an illustration of the instrument 

 this month. It is not so elaborate as 

 some of the foreign devices, which 

 are no more efficient, so far as we 

 are able to judge. Some minor im- 

 provements have been made since 

 the cut was prepared, to facilitate the 

 removal of the pan and in the move- 

 ment of the block which carries the 

 knife. It will cut successive sections 

 without interruption 

 an inch in thickness, 

 better than give the description of the 

 makers, which is as follows : — 



' The base, curved arm, upright 

 and V-shaped beds are made of one 

 continuous casting, thus insuring ex- 

 treme rigidity, without excessive 

 weight. The knife-carrying block 

 is fitted in the angular way and rests 

 upon five points ; this latter feature 

 insures the least friction and conse- 

 quent ease of movement with the 

 greatest stability, and is the nearest 

 approach to a perfect plane. Con- 

 tained in the block is a spring which 



3'u^ to ^.^0 of 



We can do no 



