The raison d'etre of the experiments described here is explained in the following quotation from A Preliminary Note on Radiant Body-heat and the School Ventilation Problem, by T. In these ways two of the three forms of body heat loss are accomplished, but as for the third form of radiation - it seems seems that very little experimental work has been done. The prosecution of this study was authorized by dr. Duffield, executive secretary of the New York City Ventilation Commission, says.
At the suggestion of the New York Commission on Ventilation, the Smithsonian Institution is conducting a study on the amount of body heat loss due to radiation, especially as it impacts children in the classroom. A detailed description of the instrument and the tests performed on it are given in Smithsonian Miscel-. It is necessary to determine what part of the total radiation of an entire hemisphere enters through this opening.
That is, multiplying 2.45 by the square of the current, in amperes, required to compensate, we get, in calories per square. We can get a baseline for this by calculating the skin temperature, assuming it is "black", and comparing it to observed temperatures taken directly.
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PRELIMINARY EXPERIMENTS IN STILL AIR
Melikeron was clamped in a vertical position at a suitable height (about i m.) and remained unchanged throughout the work. The subject stood or sat in front of the instrument in such a way that 5 to 0 cm of skin or clothing was exposed. However, the difference in temperature between the surrounding air and the shutters and the hall caused a.
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Hold the device by the wooden handle and lightly press the four loops of the spring wire p onto the surface whose temperature you want. There is no substrate at the junction except for a single silk thread, so there is no possibility of heat build-up and causing excessive temperatures. With a series of changes in the temperatures of the two baths, a graph (Figure 6) of the relationship between the deflection of the galvanometer and the temperature difference was created.
By carefully keeping the whole set-up—galvanometer, scale distance, electrical resistance and.. scale, the zero of the galvanometer was always kept exactly in the center of the scale.
BACK 7.— Sketch showing l)ody position numbers
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The value of the total radiation of the subject is obtained somewhat empirically as follows: The whole surface (see Notes to Tables, p. 26) is divided into sections.
PRELIMINARY CALORIMETER EXPERIMENTS
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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 heat loss 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 were made with each calorimeter, and in each test the radiation loss was determined with the temalikeron and the thermocouple, following exactly the method described above as applied to humans.
First, the radiation loss of the horizontal calorimeter is 6 or 7% less than the vertical one. Second, in the March 3rd test, with air movement of about 300 feet per minute, radiation is only 47% and convection has increased to 53%. This is an indication of the low emissivity of the metal surface compared to the fabric.
CALORIMETER TESTS WITH CLOTH WALLS
Accordingly, brown canton flannel cloth was hung forming a curtained room 2^ meters high and li by 2 meters in area, enclosing the calorimeter and with the melikeron mount projecting through the curtain. For part of the tests, an air current with a known velocity was admitted from an electric fan outside the curtain through a hole in the cloth. The motor of the electric fan was used on storage batteries to ensure a more constant airflow.
The results of these tests can be found in Table D. Table F is a condensed summary of both Tables C and D. From these tables a number of conclusions can be drawn:. I). The amount radiated from the horizontal cylindrical calorimeter is approx. 7% less than from the vertical cylindrical calorimeter. Much more emphasis can be placed on the measured wall temperatures on the fabric walls.
RELATIONSHIP BETWEEN MELIKERON AND THERMO- ELEMENT RESULTS
The temperatures of the water jacket are therefore given in all tables and the differences room temperature minus the temperature of the water jacket are recorded in table G. No difference is observed in the temperatures of the walls between the melikeron and the thermocouple - which could be said to be expected, since the wall is always close. Of the remaining observations, the Melikeron minus Thermoelement skin difference is much greater than any other group.
For comparison, all other groups, eg, clothing, hair, shoes, and calorimeter, are merged into one group at the bottom.
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AND IN MOVING AIR
As the temperature of the room (and thus the wall) increases, the ratio decreases significantly. On the side facing the fan, the clothing temperature drop is about a third greater than the skin temperature drop.
GENERAL DISCUSSION
NO. 6 BODY RADIATION ALDRICH 21 temperatures we can compute from the Stefan formula the average
It is then likely that since the average outside temperature was actually only i°5 above that of the measured day, the wall temperatures of table B must have been several tenths of a degree lower. This correction requires a reduction in the skin and clothing temperatures of approximately the same magnitude as the wall temperature correction just mentioned. It is a happy accident that the difference in temperature between the body surface and the walls therefore remains almost the same and the average radiation values in table B remain unchanged.
The adult basal metabolic rate (determined from . Du Bois's graph) is higher in the first series because the 3 adults were two male and one female, average age 31, while the adults in the second series were both female and average age 43. At normal indoor temperatures, in still air and with the subject normally clothed and at rest, the major heat losses will be distributed as follows: The loss by evaporation of water from lungs and skin (as stated by Du Bois, seep 14) is 24% of the total. It is interesting to compare this with a statement by Rubner (see page 20, Leonard Hill, The Science of Ventilation and Open Air Treatment) that “for an average man, in still air, the loss of heat.
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SUMMARY OF RESULTS
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NOTES ON TABLES Temperatures are given in centigrade degrees
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