THE NATIONAL PHYSICAL LABORATORY 289 



was incorporated with the Laboratory and constituted the Observatory 



Department, under the able superintendence of Dr. ( l,.u!, Chree, F.R.S. 

 The Physics Department included Division, for Electri. ,eral Electrical 



Measurements and Fundamental Units), Thcn.ioim-trv, Me trology,and Metal- 

 lurgy. Divisions for Optics, Electrotechnics and Photometry, and 

 Prediction were added in the following year. 



The history of the Laboratory since 1902 has been one of continual growth, 

 involving the extension of the existing Divisions of the work, and the formation 

 of new Departments. The staff at Teddington at the end of 1902 numbered 

 twenty-six persons : in addition to the Director there was one Superintendent, in 

 charge of the Engineering Department, and four Assistants, three of \vhom 

 were Heads of Divisions of the Physics Department. In January 191^! th. 

 staff at Teddington numbered 136, including three Superintendents, one 

 Senior and five Principal Assistants, and seventeen Assistants, in addition to 

 Junior Assistants and other scientific workers. The Divisions of the Physics 

 Department were all originally housed in Bushy House. In 1904 a proini-. 

 was received from the Treasury of a further grant, to be spread over a number 

 of years, towards the additional buildings and equipment which had become 

 necessary. Buildings for Electrotechnics and Metrology were accordingly 

 planned. 



The Electrotechnics building was completed early in 1906, and was formally 

 opened by Viscount Haldane in June of that year. A donation of .5,000 

 towards its equipment was shortly afterwards received from Sir John Brunner. 

 This enabled satisfactory arrangements to be made for the testing of electrical 

 instruments of all kinds, and for photometric work. A 100,000 volt trans- 

 former for insulation tests was installed later. 



The Metrology Building was completed in 1907, but was not occupied till 

 the following year. It was specially designed to secure the constancy of tem- 

 perature essential for the carrying out of length-measurements of the highest 

 accuracy, and a long mural base was provided for testing on the flat, or in 

 catenary, surveying tapes up to 150 feet in length. This Division also deals 

 with measurements of area and volume (e. g. the testing of areameters and of 

 glass vessels), while more recently the work of verification of masses has been 

 transferred to it. In 1907 the Laboratory was requested by H.M. Commis- 

 sioner of Police to undertake the testing of taximeters of the London cab 

 service, and this work was also entrusted to the Metrology Division. The 

 majority of the tests of taximeters are carried out at Teddington, but for the 

 re-testing of previously verified instruments a Taximeter Testing Sub-Station 

 was provided at Lambeth. Recently, in 1911, an extension has been added to 

 the Metrology Building for the re-erection of the standard screw-cutting lathe 

 of the War Office. 



The provision of the Electrotechnics and Metrology Buildings left room for 

 the further expansion of the remaining Divisions in Bushy House. The 



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