Page:Popular Science Monthly Volume 88.djvu/81

Popular Science Monthly

HE city of Boston has recently put into service a versatile motor truck that serves in many capacities. When equipped with a dumping body it is a most efficient ash collector, but when equipped with its nine hundred gallon tank body, however, the truck makes its best showing. In this form it may be used either as a street sprinkler, to supplant three water carts, or as a street oiler, in which capacity it covers twelve thousand five hundred square yards in the short time of eighteen minutes. The forty regular sprinkling nozzles are assisted in their work by a rotary pump which raises the pressure to forty pounds, and this pump is also capable of removing the contents of the tank through a side opening, thus saving labor of discharging it at the top.

In cases of isolated fires, as among lumber piles, the truck with its powerfulpump becomes an efficient fire fighting appliance. It throws a stream of water of equal power to the ordinary fire engine and can get to the scene of the conflagration quickly.

Authorities in the city state that the truck easily accomplishes the work of six horses and two drivers.

WOMAN can talk longer than a man, and does so because she uses less force by a larger percentage than a man does. A German professor has proved by actual and very delicate measurements that the baritone singer uses far more energy than either. The range of voice differs greatly, so the percentage varies to the same extent, but as a general result it was proved that a tenor uses only from one-seventh to one-sixteenth of the lung power of the baritone or bass. The difference in the force used by the contralto and soprano is very marked, and the contralto who sings in very deep tones uses at least ten times the force of the soprano.

The explanation is so simple that it is surprising that it was not thought of long ago. It has long been known that the tenor or soprano brings the vocal chords together and keeps the edges vibrating only by the emission of air. The bass or contralto leaves the space between the chords wider open, and has to vibrate much more of the membranes.

CCORDING to advices from India, there is no reason why small electric vehicles should not replace the rickshaw in hill stations, where these are now in general use. The overall dimensions of the vehicle need not be over eleven feet by five feet.