THE NATIONAL PHYSICAL LABORATORY. 143 



i:^ too little, but it is all we can do with our present building. The 

 necessary pumps are being fitted to give the pressure and we shall have 

 a lift set up along the column so that the observer can easily read 

 the height of the mercury. 



This column will serve to graduate our standard gauges up to 20 

 atmospheres, above that we may for the present have recourse to sojne 

 multiplying device; a very beautiful one is used at the Eeichsanstalt 

 and by Messrs. Schaffer and Budenberg, but we are told we must 

 improve on this. 



Again, there are the ordinary gauges in use in nearly every engi- 

 neering shop. These in the first instance have probably come from 

 Whitworth's or nowadays, I fear, from Messrs. Pratt & Whitney or 

 Brown & Sharp, of America; they were probably very accurate when 

 new but they wear, and it is only in comparatively few large shops that 

 means exist for measuring the error and for determining whether the 

 gauge ought to be rejected or not. 



Hence arise difficulties of all kinds. Standardization of work is 

 impossible. The new screw sent out to South Africa to replace one 

 damaged in the war will not fit, and the gun is useless. A long range 

 of steam piping is wanted; the best angle pieces and unions are made 

 by a firm whose screwing tackle differs slightly from that of the fac- 

 tory where the pipes were ordered. Delays and difficulties of all kinds 

 occur which ready means for standardization would have avoided. 

 Here is scope for work if only manufacturers will utilize the opportuni- 

 ties we hope to give them. 



In another direction a wide field is offered in the calibration and 

 standardization of glass measuring vessels of all kinds — flasks, burettes, 

 pipettes, etc. — used by chemists and others. At the request of the 

 Board of Agriculture we have already arranged for the standardization 

 of the glass vessels used in the Babcock method of measuring the butter 

 fat in milk and in a few months many of these have passed through our 

 hands. We are now being asked to arrange for testing the apparatus 

 for the Gerber & Leffman-Beam methods, and this we have promised to 

 do when we are settled at Bushy. Telescopes, opera glasses, sextants 

 and other optical appliances are already tested at Kew, but this work 

 can and will be extended. Photographic lenses are now examined by 

 eye; a photographic test will be added. And I trust the whole may be 

 made more useful to photographers. 



I look to the cooperation of the Optical Society to advise how we 

 may be of service to them in testing spectacles, microscope lenses and 

 the like. 



The magnetic testing of specimens of iron and steel again offers a 

 fertile field for enquiry. 



If more subjects are needed it is sufficient to turn over the pages 



