288 SECTIONAL TRANSACTIONS .—A, G. 
capacity, as well as low conductivity, is a desirable quality of insulated 
vehicles. ‘The low density of appropriate insulators is also advantageous 
from the standpoint of haulage costs, but adequate endurance and retention 
of thermal properties affects the choice of material. Other good features 
aimed at in the vehicles are air-tightness, size and dimensions to accommo- 
date full loads, and ease of cleansing. With mechanically refrigerated vans, 
thermal capacity is less important since pre-cooling is easy. But mechanical 
refrigeration involves a large unit, and is economical only for long-distance 
regular traffic. For small vehicles, in random service, refrigeration by 
solid CO, is generally very convenient, but immersion in the sublimed gas 
affects certain food products detrimentally. If, on this account, the gas is 
led into the insulation space, the choice of a suitable insulating material is 
affected. 
Mr. A. F. Durron.—The equivalent temperature of a room and its 
measurement. 
The traditional method of determining the temperature of a room is by 
means of a thermometer, and until recently neither the cooling effect of 
draughts nor the influence of the temperature of the walls has been fully 
appreciated. Although in terms of our sensations we say, ‘ It is colder now 
that the sun has gone in,’ or ‘ Come round the corner ; it will be warmer 
out of the wind,’ there has been’ no scale of temperature to enable us to 
express how much colder or how much warmer. 
The temperature of an environment with air and walls at different degrees 
is not easily specified. From the point of view of human comfort it is the 
rate at which heat is lost by the body which seems to be important. ‘The 
equivalent temperature of an environment has been defined as that tempera- 
ture of a uniform enclosure in which, in still air, a sizable black body at 
75° F. would lose heat at the same rate as in the environment. This scale 
of temperature does not extend above 75° F. At high temperatures changes 
in the humidity cease to be immaterial so far as heat losses from the body 
are concerned ; the environment, moreover, is warmer than necessary for 
comfort. 
In 1929 an instrument was constructed for recording equivalent tempera- 
ture. This instrument, which is called a eupatheoscope, was designed for 
use in researches on heating and ventilation. It is somewhat cumbrous and 
the need has now been felt for a simpler instrument for general use. It has 
been found that the equivalent temperature of an environment can be com- 
puted from the rates of cooling of two large-bulbed thermometers heated 
to 75° F., one of the thermometers having a silvered bulb. 
To simplify the computation a special face has been fitted to an ordinary 
stop-watch, which enables the equivalent temperature to be evaluated from 
the cooling times by the mere addition of two numbers. 
Mr. T. C. Ancus.—Physical tests of the properties of clothing based on 
physiological standards. 
In a research intended to provide a simple method for determining the 
heat-retaining properties of clothing materials, it became apparent that the 
value of results may be small if the physical test conditions depart too far 
from the physiological state and environment of the clothed human body 
in cool air. 
The insulating properties of a cloth are measured by determining the 
amount by which a covering of the cloth will prevent the cooling of the 
