Fkbkuarv. 191: 



KNOWLEDGE. 



79 



scope is placed (see Figure 80) is fastened to a pivoted block, 

 which cairics the lamp and travels on " domes of silence." 

 and when it is moved (he lamp move.-; with il and the lighting 

 is not disturbed. 



Figure 80. 

 .\ new Microscope 'I'lav-. 



for it to shew any sign of loss of time, or slackness on 

 snddenly reversing the direction of its travel. The entire 

 mechanism of the fine adjustment is contained in a cavity 

 millcdont of the solid phosphor-bronze limb of the instrument, 

 which is so shaped that it can be conveniently lifted by the 

 back without tension or strain being put on to any critical part. 



The snbstage is focussed by means of a rack and pinion. 

 It has complete centring adjustments and the portion which 

 carries the condenser can be swung aside out of the optic axis. 



The inclination axis is placed well above (he stage, so that 

 when the instrument is brought to the horizontal position or 

 inclined, the equal distribution of weight on either side of the 

 centre of gravity renders it exceptionally steady and rigid. 



Throughout this whole series Messrs. Swift have adopted 

 solid ground-in slides and fittings, in place of the sprung 

 fittings which, on account of want of st.ibility and life, they 

 gave up some years ago. 



THF PHOTO-MICKOGK.\PHlC SOCIETY.— It may 

 interest those who combine the camera and microscope to 

 know that the above recently-formed society is now- established 

 on a firm basis of membership, craftsmanship and enthusiasm. 

 .\t the moment of writing there are nearly fifty members, and 

 ;it each meeting additions arc being made. The meetings arc 

 held on the second Wednesday of each month, at S p.m.. during 

 the winter end of the year, ;.c".. October to .^pril. both inclusive, 

 rhe annual subscription is five shillings, the place of meeting 

 the Gardenia Restaurant, Catherine Street (next door to 

 Drur>- Lane Theatre, on the Strand side). At the September 

 meeting Dr. Rodman gave an able lecture, showing that 

 photo-micrography co\ered a very wide field of work ; that it 

 need not be an expensive hobby; that ordinary photographic 

 and microscopic apparatus could readily be adapted lor the 



NEW MICROSCOPES. — A new series of five Microscopes 

 has just been brought out by Messrs. James Swift and Son. 

 The instruments are identical, except for the stages, which 

 range from the simplest to the most comprehensive. The first 

 in the series has a plain rectangular stage with spring clips, 

 the second has a vulcanite-covered centring rotating stage, 

 the third, which is shown in Figure SI, is of the ordinary 

 mechanical type, now so very widel>' in use, the vertical 

 movement of which is actuated by a fine rack and pinion, and 

 the horizontal by a steel multi-thread screw. Both movements 

 have verniers which read to one-tenth of a millimetre. The 

 opening in the top plate is so set that it is impossible for the 

 stage to run foul of the condenser. The ne.\t stand in the 

 series is fitted with the firm's "" I. M.S."' Mechanical Stage, 

 which gives thirty millimetres range vertically, and is so 

 designed that the entire surface of a three inches by one inch 

 slip can be systematically examined. This is accomplished by 

 giving the horizontal s<rew movement a range of two and 

 a-half inches and allowing of the fingers which grip the slide 

 being moved against a vernier half an inch on either side of (he 

 normal cen(ral position. These fingers are not dependent 

 upon a spring to hold the slide, but are pressed against it by 

 small milled heads. By undoing a small clamp screw the 

 horizontal movement can be entirely removed, leaving a large 

 flat stage suitable for accommodating a Petri dish. The last 

 instrinnent in the series has this same " I. M.S. " stage, but it 

 is mounted on a centring rotating base with clamps to all 

 movements, and so is provided with every adjustment which it 

 is possible to incorporate iij a microscope stage. 



The particular microscope illustrated was built at the 

 suggestion of Professor Herbert Jackson, of King's College, 

 London, for the use of a research chemist and analyst. For 

 this reason it is fitted with a swing-out polariser and a Glan- 

 Thompson prism analyser in the body, so mounted that it is 

 capable of complete rotation. 



The fine adjustment fitted to these stands is actuated by 

 two milled heads, one on either side of the limb, that on the 

 right carrying a divided drum, each division of which is equal 

 to a movement of the body of -001 milHmetre.. The move- 

 ment of this adjustment is stopped at each end and a range of 

 three millimetres is allowed. Special attention has been given 

 to the design of the adjustment, so that it is an impossibility 



FlGUlu-; SI. 

 A new Microscope by Swift. 



work by any average handy man : and that even high magnifi- 

 cation work presented no real difficulties that a modicum of 

 care and patience could not overcome. The second discourse 



