No. 53 644. 



Luminosity. Photometers. 



467 



53 640. 1 : 2,5. 



53 643. 1 : 12. 



53 644. 1 : 15. 



53,633. Photometer after Wingen, for determining intrinsic brilliancy, Figure; benzene s d - 

 lamp with optical flame measuring apparatus after Kriiss, for a range of 1 500 metric 

 candles . 4. 0. 



This photometer is constructed on the same principle as the preceding apparatus, hut admits 

 of more accurate and extensive measurements. 



53.634. - - idem, with Hefner Lamp 



53.635. 3 Demonstration Photometers after Lambert (Eumford), Eitchie and Bunsen, modified 

 by Kolbe (Ztschr. f. d. phys. u. chcm. U. 1, 1887 88, p. 193), without optical bench, 

 together 



53.636. Photometer Screen after Topler, on stand 



53.637. Photometer after Bunsen, Figure (cf. W. u. E. phys. Prakt., p. 231, Fig. 130), 

 with house, on stand 



The photometer corresponds to that used in practice. The grease-spot screen is enclosed, along 

 with two tilted mirrors, in a sheet iron box open at both sides; to the side of this is the adjustable 

 candle holder. 



53.638. - - idem, with tape measure, for determining the distance of the source of light 

 to be measured from the photometer 



53.639. Photometer after Bunsen, Figure, with divided circle and rotary photometer 

 house, to enable measurements to be made upon light sources from various angles . 



53.640. Standard Photometer Bench, Figure, for testing gas flames, with two graduations, 

 which give the candle power direct, with Photometer Head after Bunsen, cf. No. 53,637 



The bench is constructed of iron and is 2,50 m long; the one graduation enables readings to 

 be taken when the distance between Hefner lamp and photometer screen is invariable, i. e. when the 

 lamp is on the carriage; the other graduation corresponds to the case of botli luminous sources per- 

 manently set up on the ends of the bench. 



53,641. - - idem, 

 Equality . . 



with Lumner-Brodhun Photometer Head, cf. No. 53,653, for setting at 



53.642. --idem, for setting at Equality and Contrast; for the most accurate measurements 



53.643. Photometer after Eumford (W. D., Fig. 261 [247]), Figure, with 2 rules . . . 



53.644. Photometer after Bouguer, Figure, foi measuring luminous intensity by com- 

 paring two adjacent illuminated surfaces, with 2 rules 1. 4. 



Regarding Apparatus for Testing Illuminating Gas for its sulphuretted -hydrogen content (also self-recording), its ammonia 

 and carbonmonoxide and for testing the specific gravity, etc., kindly ask for quotations. Cl. 6040, 5999, 6034. 30* 



10.10.0 



3. 5.0 

 0. 12. 



1. 10. 



1.16.0 



3. 0.0 



10. 10. 



15. 10. 

 17. 0.0 

 0. 10. 



