Page:Popular Science Monthly Volume 92.djvu/733

 Popular Science MonihJji

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��Carelessness and What It Means in Forest Fires

DURING the year 1917 our National forests were devastated by 7,814 forest fires. According to the report of the Forest Service of the Department of Agriculture all these destructive fires, with the exception of 2,132, which were caused by lightning, could have been pre- vented; 952 were undoubtedly incendiary fires, while the rest were due to pure carelessness of campers, hunters, rail- roads, settlers or travelers.

��Applying the Fireless Cooker Principle to the Delivery Wagon

EVERYONE, nowadays, knows the principle of the fireless cooker. Interpose a sufficient layer of insulating material between the atmosphere and the food which is to be kept hot and you reduce the amount of heat radiated. The principle is also applied in keeping chilled food cold. The insulating ma- terial used is mixed wool, asbestos, or even hay.

The same principle has now been suc- cessfully applied to delivery trucks and packing boxes. One of the large express companies has been making experiments this winter in St, Paul, where the tempera- ture was way below zero. Cut flowers, and other very delicate goods, were loaded directly from trains into these cold-proof boxes, and preserved until they could be delivered, in spite of the severe cold. Motor-trucks and wagons were also successfully equipped in this manner, in- sulated with paper, canvas and felt.

���This model " patient " is for the training of dental students at Iowa

Dental Practice on Teeth That Never Ache

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���These delivery wagons are made on the fireless cooker principle, with non-conducting walls, bottoms and roofs

��EFORE dental students are per- mitted to practice upon patients in the clinic they must undergo a thorough training in the science and technique of dentistry at their college. In order to give a dental student the experience of working upon a model closely resembling human jaws and under conditions such as would confront him in his work at the clinic. Dr. F. H. Volland of Iowa City, la., has invented the device shown in the ac- companying illustration.

The model jaws, with bone teeth im- bedded in the gums, are fastened to an adjustable arm supported by a pedestal. These jaws may be placed in any position which the jaws of a patient in the dental chair might possibly assume. Not until the student has learned the technique of fill- ing teeth, capping or crown- ing them and doing bridge work on this model will he be permitted to try his skill upon the patients in the clinic. The University of Iowa uses the model with succ?ss.

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