With refrigerator cars and refrigerating plants on shipboard, fruit from the far west and from tropical lands may be brought to our breakfast table. Meats from northern slaughterhouses may be transported in perfect condition into hot southern climes. There are also certain industries which are dependent on the use of the low temperatures. In breweries, dairies, margarine factories, etc., refrigeration is of the utmost importance, and refrigerating machinery is used for cooling and drying the air blast for blast furnaces. In some few places refrigerating machinery is used to cool buildings in warm weather and make life more bearable in summer weather. It is highly probable that refrigeration of dwellings will be more and more extensively developed. In winter time we can make the climate in our houses anything we please. Why should we not control the indoor climate in summer time as well? ABSOLUTE ZERO The volume of a gas varies inversely in accordance with the pressure to which it is subjected, and also directly according to the temperature. If we start with a gas at the freezing point (32 degrees F.) and reduce its temperature 1 degree (or to 31 degrees F.), we find that the volume of the gas is reduced 1/492.6 of its original volume, provided, of course, that we do not vary the pressure on it. In fact, for every reduction of 1 degree below the freezing point there is a reduction of 1/492.6 of its volume, and for every degree of increased temperature there is an increase of 1/492.6 of the volume. From this it is assumed that at 492.6 degrees below the freezing point, or 460.6 degrees below zero F., we will reach the absolute zero, or the point at which there is no more heat in the gas. We have not yet succeeded in reaching the extreme of low temperature, although we have come very near it in laboratory experiments. Helium is liquefied at -448 degrees F., which is very near to the absolute zero. At the other end of the scale we have attained enormously high temperatures. The heat of the electric arc, for instance, is between 6,500 and 7,200 degrees F., and that is the highest degree of temperature that we have been able so far to attain. Human life occupies a very limited zone in this range of temperatures. We must maintain our blood at a temperature of 98 degrees F. A variation of 8 degrees either way is fatal. By piling on heat insulators, such as fur clothing, to retain the heat of our bodies and keep it from flowing out too rapidly, we can maintain the blood temperature at 98 while the surrounding atmosphere may be 70 or 80 degrees below zero. There are internal fires within us that generate heat which radiates from the body, and by checking this radiation by suitable clothing we can maintain our blood at the normal temperature.