398 



KNOBLAUCH OX RADIANT HEAT. 



platinum, mercury, copper, lead, bi'ass, or any other metal or 

 alloy. 



The following table shows how great this agi'eement of the 



Table XXIX. 



VII, 



milli- 

 metres. 



Substances 

 inserted. 



Deflec- 

 tion by 

 direct 

 radia- 

 tion. 



Deflection 

 after the 

 insertion 



by the 



unreflected 



rays of the 



Argand 



lamp. 



Deflection after the 



insertion when the heat 



of the Argand lamp is 



reflected by 



Birch- 

 wood. 



Cork. 



Maho- 

 gany. 



Deflection 



after the 



insertion 



by the 



unreflected 



rays of the 



Argand 



lamp. 



15 

 14 

 1-4 

 4-4 

 .37 

 1-4 



1-5 

 1-4 

 14 



4-4 

 37 

 1-4 



Red glass 



Blue glass 



Alum 



Rock salt 



Calcareous spar 

 Gypsum 



13° 



Red glass 

 Blue glass 

 Alum 



25° 



17° 



Rock salt 



Calcareous spar 

 Gypsum 



30° 



7-67 



5-92 



4-33 



22-81 



15-44 



1275 



10-66 

 9-42 

 6-83 



27-00 

 18-00 

 14-25 



8-17 



6-33 



5-50 



22-81 



18-62 



15-69 



11-75 

 9-25 

 8-42 



27-00 

 21-25 

 1800 



8-08 



6-33 



5-50 



22-75 



18-50 



15-69 



11-58 

 917 

 8-33 



27-25 

 21-00 

 18-00 



8-17 

 6-42 

 5-50 

 22-88 

 18-56 

 15-69 



11-75 

 9-17 

 8-33 



26-90 

 21-25 

 18-25 



7-87 



6-25 



4-96 



22-75 



15-33 



12-33 



32° direct 



21-00 



16-25 



11-25 



40° direct 



36-50 



25-75 



1975 



7-91 



6-29 



4-91 



22-67 



15-17 



1208 



21-00 

 16-50 

 11-75 



36-75 

 25-50 

 19-75 



The comparison of the heat reflected by some perfectly hete- 

 rogeneous surfaces led to the same results as the experiments 

 just detailed. 



Thus, the rays of heat reflected by green oil-cloth, which 

 passed through the red glass, produced a deflection of 7°'0, 

 those reflected by white calico, which were transmitted through 

 the same plate, a deflection of 8°'5, when the needle had de- 

 viated 13° before the insertion; and those passing through cal- 

 careous spar produced in the first instance a deflection of 18°, in 

 the second of 20°*81, when the thermoscope by the direct action 

 of the reflected heat indicated 25°. 



The heat reflected by yellow marble and birch- wood, however. 



Table XXX. 



VIII. 



Thickness 

 in miUim. 



1-5 

 1-4 



1-4 



4-4 

 3-7 



1-4 



Substances inserted. 



Deflection 

 by direct 

 radiation. 



Deflection after 

 the insertion by 

 the unreflected 



rays of the 

 Argand lamp. 



Red glass 

 Blue glass 

 Alum 



Rock salt 



Calcareous spar 



GjTisum 



13° 



25° 



7-75 



4-92 



3-67 



22-38 

 14-38 



11-81 



1 after the insertion 

 lamp is 





Brown 

 velveteen. 



White 

 calico. 



8-08 



5-79 



521 



23-00 

 20-50 



17-19 



8-50 



6-25 



* 



5-25 



23-25 

 20-81 



17-44 



