Popular Science MonihJji 



717 



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 



B' 



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. 



