1 6 now TO WORK 



good modification of the lamp has lately been made for me by 

 Mr. Highley which possesses some advantages over the one figured. 

 It is probable that this may be somewhat modified. In the last 

 arrangement the lamp is made to slide on a horizontal bar which 

 turns on a pivot, so that the position for reflected light is easily 

 secured, pi. VII, fig. 30. A mirror 'is employed by day, and slides 

 in the same groove, or upon the same rod, as the lamp. 



The mirror, achromatic condenser, polariscope, and drawing 

 apparatus can all be readily adapted to this instrument, and it will 

 be found convenient for photographic purposes. The microscope, 

 without powers, can be purchased for twenty-five shillings, and with 

 the stand it will probably cost not more than three pounds. 



By this plan I have been able to show twelve preparations 

 magnified from 15 to 500 diameters, to a class of upwards of a 

 hundred during an hour's lecture. In about two minutes the 

 specimen may be changed and another placed in its stead. The 

 condenser, mirror, diaphragm, polariscope, &c., may also be made 

 to slide upon a rod fixed to the lower part of the stage as shown in 

 fig. 36, pi. VIII. I have had an arrangement adapted to this micro- 

 scope which enables me to use it for demonstrating structures with still 

 higher powers. In the instruments used at my lectures given in 

 1 86 1 at the College of Physicians, I was able to use successfully all 

 powers up to the twelfth (700 diameters), and I feel quite satisfied 

 that the plan will succeed equally with the highest powers which have 

 ever been made. An instrument has been made to take the T ,V- 



These hand microscopes can also be readily arranged in a line, 

 pi. VIII, figs. 33, 34, or in a six or eight-sided frame, figs. 31, 32, in 

 the centre of which the light, to illuminate all the objects at once, 

 may be placed. One advantage of this arrangement for demonstra- 

 ting to a class is that while every one can alter the focus to suit his 

 vision the preparation and light are quite out of reach. 



These simple tube microscopes have been modified in many ways 

 by various makers, and some have been made so small that they may 

 be carried in the waistcoat pocket. An instrument of this kind is 

 made by Mr. Highley. It is four inches long and only three quarters 

 of an inch in diameter, and is sold for a guinea. Not being provided 

 with the stage and spring, only one spot in the field can be brought 

 under the object glass, but it is only intended for low magnifying 

 powers which give a large field, pi. VIII, fig. 37. 



21. Dissecting Microscope. In figs. 38, 39, 40, pi. IX, is 

 shown the form of dissecting microscope devised and recommended 

 by the late Professor Quekett. Fig. 40 shows the internal ar- 

 rangement and the manner in which the mirror, lenses, and lens- 



