Making Soap from 

 Table Refuse 



Popular Science Monthly 



r 



837 



TO conserve the fats 

 contained in the table 

 refuse and dishwater of the 

 soldiers' mess, the British 

 military authorities installed 

 grease traps. The fat col- 

 lected in these traps averages 

 more than one ounce for 

 each man daily. The trap 

 consists of a tin-lined 

 wooden box, di\'idedinto two 

 compartments by a parti- 

 tion which does not reach 

 the bottorri by about four 

 inches. The dishwater and 

 the table refuse are poured 

 through a strainer into the 

 vat. As the water cools, 

 the fat forms a crust on top 

 and is skimmed ofif. 



Columbia University's fifteen-ton sundial. You can't 

 set this timepiece ahead an hour to save daylight 



This Press Can Make Two Thousand 

 Bricks of Fuel a Day 



1"^HE scarcity of coal in all belligerent 

 . countries has imposed upon all na- 

 tions the necessity of exercising great 

 economy in the use of fuels. Long before 

 the war economic reasons made it de- 

 sirable to find some method of utilizing 

 coal dust, sawdust, peat and lignites for 

 heating purposes. Briquettes were in- 

 vented and to some extent used. The 

 war reviv^ed the interest in briquettes, and 

 several new presses for making them were 

 invented. 



The device 

 shown in the pic- 

 ture is by a French 

 maker who claims 

 that one of these 

 machines, operated 

 by three men, can 

 turn out from fif- 

 teen hundred to two 

 thousand briquettes 

 daily, each weigh- 

 ing about six and a 

 half pounds. Bri- 

 quettes may be 

 made of coal dust, 

 sawdust, shells of 

 nuts or cacao beans, 

 leaves, peat, etc. 



A fuel-briquette machine which can turn 

 out about two thousand briquettes a day 



Giant Granite Ball Tells Time 

 with Great Accuracy 



A HUGE shining ball of green granite, 

 weighing more than fifteen tons, is 

 placed at the edge of the campus of 

 Columbia University, New York city, 

 for use as a sundial. It is set on a solid 

 stone base on the upper surface of which 

 are m.ounted two curved brass plates. 

 The edges of the oval shadow cast by the 

 ball fall along the two brass plates and a 

 comparison w'ill give the correct time. 

 Professor Jacoby, of the astronomy de- 

 partment, has estimated that the degree 

 of inaccuracy of the 

 sundial is never 

 more than a frac- 

 tion of a minute. 



The monumental 

 ball was a gift of 

 the class of 1885 

 to commemorate 

 the twenty-fifth an- 

 niversary of their 

 graduation. Pro- 

 fessor Jacoby, real- 

 izing the possibili- 

 ties of rendering the 

 ball useful as well 

 as ornamental, had 

 the two calibrated 

 plates attached. 



