THE WORLD'S ADVANCE 



287 



We are told that this is a "Machine War." So it is. Even the trenches of field fortifications, made 



so that a retreating army may retire to them when hard pressed, are dug by machines. This picture 



shows the experiment in machine trench digging carried out at the San Diego Exposition. A gasoline 



farm tractor was used to haul a file of sappers and digging machinery. 



the girders are raised off their bearing 

 at the movable end. The other ends of 

 the. girders are pivoted. 



By means of the crank on the side of 

 the girder the bridge is then swung by 

 winding up on the windlass the chain 

 which is anchored on one shore and pay- 

 ing out chain to anchor on opposite 

 shore. In clearing the bridge the opera- 

 tions are reversed. 



DIGGING ARMY TRENCHES WITH 

 A FARM TRACTOR 



A heavy farm tractor was recently bor- 

 rowed from the agricultural exhibit of 

 the San Diego Exposition and driven to 

 the marine barracks, where in a demon- 

 stration before Vice-President Marshall 

 and other Government officials it dragged 

 a file of sappers. The trench which re- 

 sulted formed a substantial barricade, to 

 protect the firing line of an army. The 

 demonstration was given to prove that 

 the farm tractor could perform service- 

 ably in times of war. 



FIVE MILLION FEET OF LUMBER 



SENT ABROAD TO BUILD ARMY 



AEROPLANES 



More than 5,000,000 feet of Oregon 

 spruce have been sent to the warring 

 nations of Europe within the last three 

 months from Portland, for use in the 

 making of military aeroplanes. Orders 

 for additional amounts were not filled on 

 account of the great scarcity of shipping 

 space. As a result of the heavy demand, 

 Oregon spruce has jumped from 32 to 40 

 dollars per thousand feet. The spruce 

 logs have advanced from seven and one- 

 half dollars to nine dollars per thousand 

 feet. Great Britain has been the principal 

 buyer to date. 



It is reported from Berne, Switzer- 

 land, that in Berlin and other cities of 

 Germany there has recently been intro- 

 duced a new form of food. Consisting 

 of flour, maize, dried vegetable and dried 

 meat, ^two^ cents' worth of this composite 

 food is said to be sufficient for a meal. 



