648 



Thermal Conduction, etc. 



. :)99 



55 402. 1 : 5. 



55 403. 1 : 6. 



55.399. Thermal Radiation Apparatus after Bumford, consisting of 2 cylindrical vessels, one 

 with smooth and the other with rough surface, for comparing surface radiation, with 

 2 thermometers divided in 1 / 2 degrees 



Both vessels are filled with boiling water and the time is measured which is required ; for cooling 

 down to a definite temperature. 



55.400. Thermal Radiation Apparatus after Dulong and Petit, consisting of a mercurial thermo- 

 meter with large thermometer vessel and with holder and screens 



The thermometer is heated to a definite temperature and the time measured for the thermo- 

 meter to cool down to the surrounding temperature. The experiment is repeated after covering the 

 thermometer chamber with lamp black, leaf gold, leaf silver or with different dyes. 



54,531. Gap with Micrometer Screw and Divided Drum, Fig. 54,531, p. 545 



54,530. - - idem, without Micrometer Screw or Divided Drum, Fig. 54,530, p. 545 . . . 



55,401. Surface Bolometer for measuring Badiant Heat, cf. Fig. 55,402, after Lurnmer and 

 Kurlbaum, with two Branches and protecting box with slider (Ztschr. f. Instrumenten- 

 kunde, 12, p. 81; Wied. Ann. 1892, Vol. 46, pp. 204 et seq.) 



The bolometer is based on the change in electrical conducting resistance produced by the heating, 

 on radiation, of a lamp-blacked platinum grating of extreme fineness (0.001 mm thick) fixed to a small 

 slate frame. The change in resistance is measured by means of the Wheatstone bridge combination. 



.">". 402. -- idem, with 4 Branches, Figure, with protecting box, sliders and central 

 diaphragm 



55.403. idem, Figure, with 4 branches, two of which can be illuminated alternatively 

 by lateral displacement of the apparatus (Physikalisch-Technische Beichsanstalt pattern) 



The detachable protecting box is provided with a pipe for the introduction of a thermometer. 



55.404. Linear Bolometer after Lummer and Kurlbaum, Figs. A and B, with 2 branches, 

 with mount 



In this apparatus the slate frame is provided with two fine platinum strips which are connected 

 up as adjacent branches of the Wheatstone bridge and one of which is screened off from the rays. The 

 apparatus is employed in conjunction with a spectrometer, this method of using being explained by 

 F i K. .V>.404 B. 



v>.lor>. Capsule with Slate Frame, Fig. 55,404 A, for forming a 4-branch Bolometer I' rum the 

 preceding apparatus 



Very sensitive galvanometers should be used for connecting with the bolometers (10~ 8 to 10- 9 amp. 

 sensitivity), see section "Electricity". 



Cl. 1945, 1946, 

 4104, 4543, 



s. d. 



2. 0. 



t 



2. 8.0 



1. 13. 

 1. 3.0 



3. 0.0 



4. 10. 

 5. 0.0 



3. 0.0 



]. 6. 



1951. 



