July 3, 1913] 



MATURE 



465 



mem patent flooring; the woodwork is chiefly oak, 

 the effect of which is altogether admirable. 



To take the central block of the new building first. 

 Opening on to a large central hall on the ground 

 floor are the accountant's offices and strong-room, 

 reception-rooms for visitors, and a telephone exchange 

 room; on the first floor are the director's room and 

 the secretarial offices; on the second floor, inter aha, 

 the "White Library," a publications room, and a lec- 

 ture theatre. The library is being furnished 

 by the Drapers' Company in memory of the 

 late Sir William White, to whose good-will 

 and energy the laboratory owes a great deal. 

 A brass memorial tablet records that '■The Worship- 

 ful Company of Drapers of the City of London, 

 mindful of the last wishes of Sir William Henry 

 White, K.C.B., F.R.S., gave to the Laboratory the 

 bookshelves in this library." The fittings are being 

 carried out in old oak, and the library, with its 

 panelled walls, recesses, and gallery, brings to mind 

 some of the college libraries at the older universities. 



It is anticipated that the new lecture-room will 

 afford facilities for meetings of scientific societies, for 

 many of which an annual visit to the laboratory has 

 become a recognised function. It is hoped also that 



opportunity will be afforded to the members of the 

 stafl of hearing distinguished visitors at a fortnightly 

 or monthly colloquium. 



The central block is isolated from the north and 

 south wings by fireproof doors. 



On the "ground floor of the optics division are two 

 larije semicircular arch-shaped tables made of cast- 

 iron. One of these is vertical and the other hori- 

 zontal. They are used to test the accuracy of gradua- 

 tion of theodolite circles and sextant arcs. One face 

 of each table is machined, and to it are bolted at 

 definite angles collimators pointing to the centre oi 

 the semicircle. The tables rest on isolated masses of 

 concrete weighing some 20 tons; and to avoid 

 troubles due to seasonal and extraneous temperature 

 changes, the tables and supports arc hollow through- 

 out, and are kept at uniform temperature by circulat- 

 ing water through them. In the same room is a 

 tilting table with standard wedges for testing clino- 

 meters. The photometer and spectacle-lens benches 

 are mounted in an adjoining room, along one end of 

 which is a movable partition which can be removed 

 when extra long-focus process lenses are being tested. 

 NO. 2279, VOL. 91] 



A rapid and convenient system of light-tigln 

 blinds is a noteworthy feature of the fittings. The 

 testing of microscopes is conducted in an adjoining 

 room. 



On the first floor, a group of rooms is allotted l"i 

 testing terrestrial telescopes. One of these can be 

 completely darkened for the purpose of examining the 

 parallelism of the axes of binoculars, or the illumina- 

 tion of cross wires. Test objects and scales of various 

 forms, and at distances up to 400 yards, have been 

 erected. 



A long ferro-concrete balcony (which, by the way, 

 was cast in one mould complete) extends along the 

 outside of the first floor. This will enable open-air 

 tests to be made on instruments. 



On the second floor, the equipment for examining" 

 photographic lenses is grouped in adjoining room-.. 

 Here are, for example, the Hunter apparatus for 

 obtaining a numerical estimate of definition ; the Beck 

 bench for measuring focal length, astigmatism, curva- 

 ture of field, &c. The testing of photographic shutters 

 is carried out here, by the use of vibration galvano- 

 meters tuned to resonance with electrically-driven 

 tuning-forks or vibrating bars. 



Next is the room devoted to spectroscopy, and in 

 particular to the examination of re- 

 fractometers and spectrophotometers. 

 A feature of the room is a large 

 roller shutter by means of which the 

 room can be readily divided into two. 

 The shutter is provided with suitabl ■ 

 apertures, to fit the various instru- 

 ments under test, and will be 

 brought into use when it is impor- 

 tant "that the eyes of the observer 

 should not be exposed to bright 

 lights during the test. 



The remainder of the rooms are- 

 given up to the general photographii 

 work of the laboratory. There is an 

 unusually well-designed and venti- 

 lated suite of dark-rooms with light- 

 trapped doors and the like. Other 

 rooms are speriallv designed and 

 illuminated for photographing appa- 

 ratus and diagrams. 



The roof of the building is flat 

 and asphalte-covered, and on it at 

 one end is arranged an observatory. 

 This is to be fitted with a telescope 

 with an equatorial mounting, and a dome. The tele- 

 scope is designed so that object-glasses sent for test 

 can be mounted as in actual use. 



The north wing contains the packing-rooms and the 

 associated clerical offices, together with store-rooms 

 and wood and metal workshops. Arrangements have 

 been made here for the engraving of instruments 

 with the familiar XPL mark-outward and visible sign 

 that an instrument has passed its tests. Copious pro- 

 vision was necessarv for dealing with the packing 

 and unpacking of cases containing instruments, the 

 handling of which under the old arrangements was 

 fast becoming a problem owing to the volume of stun 

 which had to be dealt with. There is a large Way- 

 p-ood lift, to which leads a sunk track for wide rubber- 

 wheeled trolleys. Thus these lain, 1 an be run on the 

 lift and so to the various corridors and rooms, ["here 

 is .1 second lift to the workshops. In this block, a 

 common-room for the laboratory boys has been pro- 

 vided. . ., 



The foregoing description will perhaps give an idea 

 of the admirable manner in which the new building 

 has been designed for its work. 



