866 



Popular Science Monthly 



Two dial hands indicating mileage are geared up to 

 the two rear rollers. The cyclist who first succeeds 

 in making the prescribed number of revolutions wins 



The Amount of Energy 

 Expended in Coughing 



IF you cough once every fifteen 

 minutes for ten hours you 

 expend energy equivalent to two 

 hundred and fifty units of heat, 

 which is equivalent to the nour- 

 ishment contained in three eggs 

 or two glasses of milk. So says a 

 German who has specialized on 

 the waste of energy in coughing. 

 At a normal rate we expel air 

 from the chest at the rate of four 

 feet per second, but in violent 

 coughing we expel it at the rate 

 of three hundred feet a second. 

 Thus a persistent cough not only 

 weakens the constitution but it is 

 a direct cause of emaciation ac- 

 cording to the same authority. 

 Such weighty statistics lead to a 

 reiteration of the oft-repeated in- 

 junction, "never neglect a cough." 



They Make Twenty Miles an Hour 

 but They Never Move an Inch 



THE fun and exercise given by a good 

 bicycle race need no longer be ham- 

 pered by the condition of the weather. 

 A machine has been improvised in one of 

 New York's East side recreation centers 

 upon which the race can proceed indoors, 

 whatever the weather. 



The machine is made up of two sets of 

 rollers, three rollers in a set, on which the 

 competing cyclists ride side by side. The 

 two rear rollers of a set support the rear 

 wheel of the bicycle. When the cyclist 

 pedals ahead, the rear 

 rollers are turned and a 

 belt attached to a pulle}' 

 on one of them makes the 

 front roller of the set turn 

 also. Both wheels of a 

 bicycle are therefore kept re- 

 volving so that the balancing 

 action due to motion is equiva- 

 lent to that obtained on the 

 open road. 



The progress of the race is 

 indicated by two hands that 

 travel over a mileage dial. Each 

 hand is geared up with a rear 

 roller of the machine. The 

 exact distance that each wheel 

 has gone is also registered. Each revolution 

 represents half a mile, and the cyclist who 

 first finishes the prescribed number wins. 



1 



A Good Automobile Signal Is 

 Accident Insurance 



AN automobile warning signal recently 

 l\ put upon the market is a whistle 

 that is operated by the gasoline explosions 

 in a cylinder of the engine. At critical 

 times the full force of the cylinder explo- 

 sions operates the whistle. A powerful 

 blast is produced which can be heard 

 above all traffic noises. 



The device consists of an air chamber 

 into which the stream of exploding gases 

 from the cylinder rushes to produce the 

 blast. A small gas-tight valve is interposed 

 between it and the top of the cylin- 

 der. This valve is very much like 

 the exhaust poppet 

 valves on the engine it- 

 self, except that it never 

 opens to blow the whis- 

 tle unless the driver 

 presses the control lever 

 for that purpose. The 

 pressing of the lever on 

 the driving wheel forces 

 down the valve into the 

 cylinder by means of 

 the wire link connec- 

 tions between the two. 

 This allows the regu- 

 larly exploding gasoline 

 to escape into the whistle instead of work- 

 ing against the engine piston. The explo- 

 sions follow each other very rapidly. 



A lever mounted on the 

 driving wheel opens a 

 valve and releases the 

 exploding gas into the re- 

 sonating sound chamber 



