AUTOMATIG ARC LAMP. 
This forms a very satisfactory illuminant for micro- 
photography, projection, dark ground illumination, etc. etc. 
The automatic mechanism relieves the operator of all trouble 
except that of switching on and off. 
No. 3329. Automatic arc lamp, 5-10 amperes, for direct 
current.... ss = ae bee ee a 
No. 3329A. Resistance 5 bee for D.C. 200- 
240 volts aos is 2, Mio 
aa s No. 3329B. Resistance 5 eee for D.C. 100- 
No. 3329 120 volts Li: 
No. 3329C. Resistance 10 amp. for D.C. 200 240 volts oe af ae i, 212 6 
No. 3329D. Resistance 10 amp. for DC. 100 120 volts 110 0 
A special model of this lamp is made for alternating current. Particulars on application. 
CARBONS FOR ARC LAMPS. 
No. 2171. Carbons, best quality 6 m/m. for No. 3635 and 3636 ... sis per doz. {0 2 3 
No. 2172. Carbons, best quality 8 m/m. for No. 3635 and 3636 .. as be ame By (6 
No. 2173. Carbons, best quality 7 m/m. for No. 3635 and 3636 . ee hance Oe2a ao 
No. 2174. Carbons, best quality 5 m/m. solid for No. 3329A (5 amps. Wee a 0» 3.°6 
No. 2175. Carbons, best quality 5 m/m. cored for No. 3329A (5 amps.).. Peet Opals 10 
No. 2176. Carbons, best quality 9 m/m. solid for No. 3329A (10 amps. i any oO 8 3 
No. 2177. Carbons, best quality 9 m/m. cored for No. 3329A (10 amps.) tens OO: 760 
LIGHT FILTERS. 
Beck Colour Filters. 
These filters are of dyed gelatine cemented between glass plates, and comprise the following 
colours: red, orange, green, blue-green, blue and purple. They are suitable for both visual 
and photographic work. 
No. 3346. Beck colour filters, set of six, 2in. x 2in., in cardboard case BAe ee On) 
No. 3347. Single filters, 2in. x 2 in., in any of the specified colours... asp Rees (ee: be) 
Wratten & Wainwright ‘‘M ”’ Filters. 
A series of filters suitable for visual observation or photography. They are of gelatine 
mounted between glass plates, the range of colours being: orange red, green, blue-violet, 
purple, orange, pure red, strong yellow, blue, pale yellow. 
No. 3333. Wratten & W SEaeRY Ss Mi filters set of nine, 2 1m. 24ine= aim 
cardboard box . bck £5 a ae See ho? a ON 
No. 3333A. As No. 3333, but of 13 in. or re it in. dia. ae aie or ais ee 2 won 04 
Chance-Parsons Colour Filters. 
This series of filters are of coloured glass. They have the advautace over gelatine filters, in 
that they will withstand heat. They are made to a thickness of 2}-3m/m. A complete range of 
colours, neutral, orthochromatic and ultra-violet filters is av ailable as follows. 
No. 1 Ruby, No. 2 Red, No. 3 Deep Orange, No. 4 Light Orange, No. 5 Green, No. 6 Blue-green 
No. 7 Blue, No. 8 Purple, No. 9 Daylight, No. 10, Dark Neutral, light transmission 7-3°%, No. 11, 
Light Neutral, light transmission 23:1%, No. 12, Dark Orthochromatic, No. 13, Light Ortho- 
chromatic. No. 14, Ultra-violet, isolating wavelength of 3000 4000 A.U. 
No. 2186. Chance-Parsons filters, 2in. x 2 in., all colours 1—13 : 2 each £0! 30 
No. 2187. Chance-Parsons filters, 2in. x 2 in., all colours 1—13, w pred poemmeachan Osrone 0) 
No. 2188. Chance-Parsons filters, 2in. x 2in., No. 14.. ~ ae = eacne  OnlOe30 
No. 2189. Chance-Parsons filters, 2in. < 2in., No. 14, worked — ee CACin ee Onltie ae G 
No. 2190. Chance-Parsons filters, 13%; in. or 12 in. dia., all colours 13) ye each 085246 
No. 2191. Chance-Parsons filters, 13 in. or 13 3 in. dia., all colours 1—13, w orked each 0 4 6 
No. 2192. Chance-Parsons filters, 1-3; in. or 133 iiedias Now =: aie He each = 06% 6 
No. 2198. Chance-Parsons filters, 133; in. or 13 in. dia., No. 14, worked =e eeach: = O10) 16 
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