SCIENCE-GOSSIP. 



2 79 



CONDUCTED BY F. SHILLINGTON SCALES, F.R.M.S. 



MiCROscoriCAi. Examination of Steel. — The 

 microscopical examination of steel and of alloys in 

 engineering laboratories is no new thing, but its value 

 and utility in the steel industries were brought by 

 Mr. C. H. Ridsdale prominently before the members 

 of the Iron and Steel Institute at their autumn meet- 

 ing. Mr. Ridsdale gave some of the results of his 

 study of soft steel up to the present time, and ex- 

 plained how he had systematised its microscopic study, 

 and adapted it to the commercial as well as the 

 scientific requirements of a laboratory where com- 

 mercial interests predominated. In the interesting 

 discussion that followed stress was laid upon the im- 

 portance of formulating a method of procedure, by 

 means of which uniformity of results might always be 

 obtained. Prof. Porter, of Montreal, stated that he 

 was engaged in equipping an expensive micro- 

 laboratory in his college at Montreal, and remarked 

 that the importance of the subject was fully recog- 

 nised both in Canada and in the United States. 



New Objective Changer. — An objective 

 changer has recently been brought under our notice 

 by the courtesy of Mr. F. W. Watson Baker. It is 

 both inexpensive and effective, and is less cumbrous 

 than that of Zeiss. Into the end of the microscope 

 tube fits a screwed ring provided with a semicircular 

 jaw beneath, the jaw itself lying immediately beneath 

 the ring and being kept against it by a spring be- 

 tween two projecting arms. Accordingly on com- 

 pressing the arms the jaw leaves a space of about a 

 quarter of an inch between it and the above ring. 

 Each objective is fitted with another steel ring only a 

 little larger in diameter than the milled head of the 

 objective. The objective, instead of being screwed 

 into place as usual, is then simply slipped into 

 position beneath the body tube of the microscope, 

 and is there securely gripped by the semicircular 

 jaw. As the ring on the objective is made to fit 

 accurately into a recess in the ring that is screwed 

 into the body tube, the objective itself is well 

 centred, though it might possibly be not quite satis- 

 factory for the highest powers. Those of our readers 

 who prefer this type of objective changer to the 

 ordinary rotating nose-piece will find this simple 

 little device useful. It is made by R. Fuess, Steglitz, 

 near Berlin, and can be obtained through the London 

 opticians. Its price, with four adapters, is only 

 fifteen shillings. 



Crouch's " Histologist " Microscope. — Mr. 

 Henry Crouch, of 92 Duncombe Road, London, N., 

 has submitted for our examination the latest model of 

 his " Histologist " microscope, which is specially 

 designed for the use of students, particularly medical 

 students. We give an illustration of the instrument. 

 The coarse adjustment is by the now customary 

 diagonal rack and pinion, and the fine adjustment is 

 of the micrometer screw type. The foot is a claw- 



tripod, and as such is perfectly steady. The stage is of 

 the horseshoe pattern, but in the microscope sub- 

 mitted to us the advantage of this was somewhat 

 discounted by the sub- stage ring being fixed in 

 position beneath the stage. The microscope itself 

 is well made and finished, and is specially de- 

 signed to withstand the rough wear and tear of a 

 laboratory. There are the usual plane and concave 

 mirrors. The objectives generally supplied are the 

 §-inch, N.A. -28, and ^-inch, N.A. -65, both being 

 arranged to work approximately in the same focal 

 plane. The apertures are moderate, as is suitable 

 for histological work ; but the objectives are excel- 

 lent ones, and will bear favourable comparison with 

 any others in the market at the same price. The 

 price of the f-inch is 15s. and of the <t-inch 30s. 

 We had also an opportunity of examining a i-inch 

 N.A. -26 at 15s., and a ^V-inch oil immersion N.A. 

 1*3 at £$. This last was a really fine lens. The 

 microscope, as described above, with double nose- 

 piece, \ and g- inch objectives, two eye-pieces, and 

 mahogany case, is sold at £7 7s., or with Abbe con- 

 denser N.A. 1 - 2, with iris diaphragm, 30s. extra. 



Histologist Microscope. 



Standardisation of Sub-stage and Draw- 

 tubes. — The Royal Microscopical Society, which 

 has already done so much for the standardisation of 

 the various parts of the microscope, and whose 

 standard for the thread of objectives, known as the 

 " Society Screw," is now adopted by opticians 

 throughout the world, has passed some important 

 resolutions with regard to the standardisation of the 

 sub-stage and of the internal diameters of the draw- 

 tubes of microscopes. There are few workers who 

 have not experienced the annoyance and difficulties 

 caused by the present want of uniformity among our 

 leading makers. The present step is yet another in 

 the direction of uniformity, though we could wish it 

 had been a more firm and decided one. As it is, it 

 will not do away entirely with the evil complained of, 



