ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



129 



in- 



the 



p. 890. 



Fig. 12. 



Microscopes at the Antwerp Exhibition.* — Dr. H. van Heurck 

 reports upon the Microscopes exhibited at the recent Universal 

 Exhibition at Antwerp. " The Microscope," he says, " is generally 

 very imperfectly represented in universal exhibitions, and the Antwerp 

 exhibition was no exception, only six firms being represented, Hart- 

 nack, Nachet, Prazmowski (Bezu, Hausser and Co.), Eeichert, Eoss, 

 and Zeiss. 



Of Hartnaek's instruments Dr. van Heurck describes Bacterial, 

 Mineralogical, and Photographic Microscopes, also his Cupro- 

 ammonia Cell (post). M. Nachet's instruments are the Large Model, 

 Petrographical, Chemical, Travelling, Demonstration, Dissecting, 

 and Double body Microscopes. Also his " Loupe-chambre-claire " 

 (post). Of Bezu's, the Mineralogical, and Large and Second 

 Hartnack Models. In each case the objectives exhibited are also 

 reported on, and the special fluid for homogeneous immersion used by 

 Dr. Hartnack described {infra, p. 133). 



Hippisley's Lens- and Slide-Holder. — Fig. 12 shows the 

 geniously simple mounting adopted by Mr. J. Hippisley for 

 lenses made of globules of glass described Vol. V, 



The lenses are secured between two pieces of 

 thin brass, one of which has its two ends turned 

 up over those of the other, and hammered down. 

 The lens thus mounted is slipped into a holder 

 of brass wire in the manner shown in the figure, 

 the slide being similarly held by another part 

 of the holder. The focusing adjustment is 

 made by pressing together the two parts of the 

 holder which are normally kept apart by the 

 " spring" of the wire caused by the turns which 

 are made in it at the bottom. Mr. Hippisley 

 describes its use thus : — 



" It is intended to be held torizontally, when 

 the focal adjustment will be found to be well 

 under command of the thumb and finger of one 

 hand. The spring of the wire allows ample 

 traverse of the lens over the field ; and by 

 judicious application of the other thumb and 

 finger the slide may be shifted longitudinally, so 

 that any part of the field can be examined with- 

 out removing the instrument from the eye. 

 The other hand makes a convenient screen for 

 the eye not in use. 



This is only one of many variations of contrivances for utilizing 

 these lenses. ' Thumb-screws ' are an abomination for slowness of 

 action and other inconveniences. A wedge I have found much more 

 useful for fine adjustment, as its operation is equally fine, and it 

 may be suddenly thrust in or. withdrawn for the beginning (or coarse 

 part) of the adjustment. But I do not think, unless it is wanted to 



* Journ. de Microgr., ix. (1885) pp. 364-75 (6 figs.). 

 Ser. 2.— Vol. VI. 



