356 PHYSICAL LABOEATORY OF GREAT BRITAIN. 



P3^ronieter gives wa}^, the furnace gases get into the wire and are 

 absorbed, and the indications become untrustworthy. We hope it may 

 be possible to utilize the silica tubes, shown here by Mr. Shenstone a 

 short time since, in a manner which will help us to overcome some of 

 these difficulties. Here is another subject of investigation for which 

 there is ample scope. 



So far we have discussed new work, but there is much to be done in 

 extending a class of work which has gone on quietly and without much 

 show for many years at the Kew Observatory. 



Thermometers and barometers, wind gauges and other meteorolog- 

 ical apparatus, watches and chronometers, and many other instru- 

 ments are tested there in great numbers, and the value of the work is 

 undoubted. The competition among the best makers for the first 

 place, the best watch of the year, is most striking, and affords ample 

 testimony to the importance of the work. Work of this class we pro- 

 pose to extend. 



Thus, there is no place where pressure gauges or steam indicators 

 can be tested. It is intended to take up this work, and for this purpose 

 a mercur^^-pressure column is being erected. Bushy House, from base- 

 ment to caves, is about 55 feet in height. We hope to have a column of 

 aV)Out 50 feet in height, giving a pressure of about 20 atmospheres; it 

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

 necessary pumps are Ijeing fitted to give the pressure, and we shall 

 have a lift set up along the column so that the observer can easilj' 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 some 

 nuiltipl^nng device. A very beautiful one is used at the Reichsanstalt 

 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 tirst 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. 



Hcjice 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 lit, 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 slightl}^ from that of the fac- 

 tory where the pipes were ordered. Delaj^s and difficulties of all kinds 

 occur which ready means for standardization would have avoided. 

 Here is scope for work if onl}' manufacturers will utilize the oppor- 

 tunities we hope to give them. 



