21 o 



Popular Science Monthly 



You can't forget your appointments if you 

 write them down on cards and place them 

 in the right compartments in this machine 



Do Your Remembering by 

 Electrical Machinery 



DO it electrically! The "remindo- 

 graph" is an application of that 

 slogan to the task of remembering. 

 It consists of a wooden cabinet 

 in which there are a number of 

 small pigeon-holes, enough for 

 every quarter hour in the day. 

 On one side of each is the time 

 of the quarter-hour to which 

 the pigeon-hole corresponds, 

 while on the other side is a 

 small electric lamp. At the 

 back of each hole are electric 

 contacts or brushes between 

 which a strip of metal can be 

 placed or taken out at will. 

 This strip can be fitted upon ?, 

 small card, and when such a 

 card is placed in a pigeon-hole 

 an electric battery circuit is 

 closed to corresponding con- 

 nections on what may be called 

 an "alarm clock." Hence when 

 you have an appointment for 

 2:15, you simply insert one of 

 the cards in the pigeon-hole 

 marked 2:15. As soon as the 

 clock points to 2 :i5 an electric 

 buzzer rings and the lamp 

 lights. This will continue until 

 you take out the card. 



Directing the Fire of a Big 

 Artillery Gun 



TO-DAY there is about as much differ- 

 ence between aiming a big gun and 

 aiming a rifle as there is between sailing a 

 superdreadnought and sailing a steam 

 yacht. It was not very long ago, however, 

 that a gun was aimed similarly to a rifle in 

 that the direction in which it was pointed 

 was obtained by sighting along its barrel. 

 But now things are not done that way. 

 The gunners in the European war, for 

 instance, are often far out of sight of what 

 they are shooting at, and the remarkable 

 hits that they make are only explained by 

 the use they make of careful scientific 

 calculations. 



To direct the fire of one of the bigger 

 guns, for example, requires that no less 

 than fifteen complicated corrections be 

 made. Each correction requires an average 

 of five adjustments, all of which must first 

 be exactly figured out by those in command. 

 The most important corrections which are 

 made are for the influence of the resistance 

 of the air, the influence of the earth's 

 curvature, and the attraction of 

 gravity on the distance the bullet 

 may be carried. In place of the 

 guess-work of previous times is 

 the use of the most advanced 

 developments in the fields of 

 mathematics, physics and 

 chemistry. 



The machine tells you how 

 much you weigh and shows 

 you what to eat to increase 



A Weighing Machine in a 

 Restaurant Show- Case 



THE latest thing in restau- 

 rant fixtures is a weighing 

 machine built directly in a 

 show-case. Doctors are begin- 

 ning to feel that the condition 

 of a person's health is usually 

 shown in his weight. When 

 you lose weight, rest assured 

 that something has gone wrong 

 and that your health has 

 suff^ered as a consequence. The 

 restaurant keeper has a legiti- 

 mate interest in keeping your 

 weight normal. The index of 

 the new scale will indicate 

 your health, and the show- 

 case will tempt your ap- 

 petite, or coax it along if you 

 have none, and will tell you 

 what you ought to eat. 



