i6 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



outside completely covered with a tight fitting jacket consisting of 

 a single thickness of brown canton-flannel cloth. The purpose of 

 the shape and covering of the calorimeters was to simulate the 

 clothed human body. Heat was lost from the calorimeter only by 

 radiation and convection, and the total loss of heat per hour could 

 be accurately determined from the rate of change in temperature of 

 the water and the water equivalent of the calorimeter. A series of 

 tests was made with each calorimeter, and in each test the radiation 

 loss was determined with the melikeron and with the thermoelement, 

 following exactly the method described above as applied to human 

 subjects. 







Fig. 9. — Diagram for coinputing solid angle exposed to melikeron. 



The results of the preliminary tests are given in table C. Several 

 interesting points appear. First, the radiation loss of the horizontal 

 calorimeter is 6 or 7% less than in the vertical. This indicates that 

 the shape of the calorimeter is important in determining the amount 

 of the convection and helps to account for the difference in convection 

 between the sphere 50% and the cylinders 70 to 80%. As noted above, 

 however, this discrepancy is also in part due to the less perfect radiat- 

 ing properties of lamp-black than of porous cloth. Second, in the test 

 of March 3, with air motion of about 300 feet per minute the radia- 

 tion is only 47% and the convection increased to 53%. Third, with 

 no cloth cover, the test of March 26 shows only 34% radiated from 

 the copper surface in still air. This is an indication of the low emis- 

 sivity of the metal surface as compared with the cloth. 



CALORIMETER TESTS WITH CLOTH WALLS 



A weakness in the experiments thus far has been the impossibility 

 of accurately knowing the mean temperature of the walls to which 

 the subjects or calorimeters are radiating. A very helpful letter from 

 Prof. Phelps of the New York Commission dated March 27, 1928. 

 suggested the possibility of standardizing the wall conditions by sur- 

 rounding the subject with cloth draperies whose temperature, closely 

 that of the air in the room, could be determined with the same thermo- 



