July 1, 1870.] 



HAKDWICKE'S SCI ENCE-GO SSIP. 



163 



MICROSCOPY. 



Improved Turn-table.— It may be of interest 

 that I should describe briefly my new form of turn- 

 table, or cell machine, by which slides are held and 

 centered, as regards their width, at the same time 

 leaving their surface entirely free, so that two, three, 

 or more cells may be formed in their length. Every 



towards (and moving) C, the other end of C— i.e. 

 D — is moved exact!?/ as much in the opposite direc- 

 tion until they approach near enough to grasp the 

 slide by its edges. The leugth of the wedge must, 

 of course, be such as to provide for about & of an 

 inch variation in the width of slides. It will readily 

 be seen that the slip may be pushed in either direc- 

 tion excentrically lengthwise, so as to allow of the 



Fig. 158. Dr. J. Matthews' Turn-table. 



one who has'used the present machine must often 

 have felt the inconvenience of the springs ; some- 

 times too strong, at others too weak, always in the 

 way, catching the fingers or the pencil, and limiting 

 the number of cells. Centering is also so uncertain 

 that several ingenious remedies have been proposed 

 and used with varying success : but none have en- 

 tirely supplanted the old form devised by Mr. Shad- 

 bolt, now in use. My plan is simple in the extreme, 

 consisting of two jaws of the average thickness of 

 a glass slide, f of an inch wide, 2| long. Each of 

 these is pivoted on the face of the turn-table by a 

 screw through its centre, each screw being placed 

 exactly equidistant from the centre of the turn- 

 table, so that the jaws are separated by a space as 

 wide as an average slide ; i.e., a full inch. Outside 

 of that space, on one side of the centre of one of 

 the jaws, is a wedge fixed by a screw, in such a way 

 as to be capable of motion in the direction of its 

 length by a slotted hole. This is all the machinery. 

 A B and CD are the two jaws, E is the wedge. On 

 placing a slip between the jaws they probably at 

 first do not touch it. If the wedge be then pushed 

 so as to approximate B to C, the jaws move on 

 their centres, so that, however far B may be pushed 



formation of "any number of cells, all of which must 

 needs be central as regards their width, if the in- 

 strument has been accurately made, which is a very 

 easy matter. I have added also a rest for the hand, 

 E, which may be turned aside on a centre at will, 

 and which I have found to be a great convenience. 

 I am informed by several persons that its price need 

 very little, it at all, exceed that of the old form. — 

 J. Matthews, M.D., at Quekett Club. 



Hornet's Tongue. — I do not remember to have 

 seen noticed in Science-Gossip the curious struc- 

 ture of the tongue of the Hornet, which it may 

 interest some of your readers to examine more 

 closely this summer. Though the general features 

 of this organ are very well displayed in the pur- 

 chased slides of the tongue prepared in Canada bal- 

 sam, it is only in the fresh specimen, or one pre- 

 pared in fluid, that the actual structure can be satis- 

 factorily discerned. It appears to me to be com- 

 posed of a number of tubes running parallel to each 

 other, and from which proceed at right angles and 

 equal distances, a number of open-mouthed pipes, 

 very much like certain musical instruments. — 

 B. H. N. B. 



