# Page:Popular Science Monthly Volume 90.djvu/882

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��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.

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���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

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