Page:Popular Science Monthly Volume 92.djvu/204

 183

��Popular Science Monthly

���K

��The four sheet-iron drums revolve sidewise but the auto sled goes forward. The long runner in front is for steering

��Skating Over Ice and Snow in a Queer Motor Sled

MOTOR sleighs have not yet been per- fected, although there is a genuine demand for them in northern countries. It is difficult to get traction on rough ice or in loose and deep snow. But sideslip of the vehicle is the most obstinate source of trouble, and the control on hills, whether going up or down, is precarious. Safe steering depends greatly on the driver's sharp eye and caution. For a tractor intended to haul loads over ice and snow, these difficulties are much ag- gravated, un- less the speed can be very low; yet such a tractor has been invented and built by Frederick K. B u r c h, of Grand Rap- ids, Mich.

��the middle, four sheet- iron drums, which also support the vehicle, are rotated: those on the right side to the left (seen from above) and the pair on the left side to the right, as if meant to scrape the road from under the middle to both sides. The drums are rounded in front to rise easily over rough spots and to facilitate steering. They carry curved (helical) chan- nel-iron ribs which grip the ground against side- slip as well as for trac- tion. This driving principle was tried on a motor sleigh at Chamonix, near Geneva, Switzerland, several years ago, but with only two relatively small ribbed drums held against the ground by springs, as the main load was supported on runners.

��before birth.

���The whale's whiskers are a horny substance used as a sieve through which food is strained

��Clumsy as it looks, a speed of thirty miles per hour is claimed for this vehicle when it is let loose on a level stretch of ice. In the photograi)h, the motor erjuipment is recognized as that of an old Ford. By means of chains mounted crosswise under

��A Whale Which Strains Its Food Through Whiskers

LL whales develop rudimentary teeth If the teeth continue to grow, the whale is put in the toothed class; if the teeth are dis- placed by a large number of flattened plates of bone or baleen, fringed at the edges, the whale is put in the whale- bone class. Baleen forms a sieve through which the whale strains all food col- The three men

��lected from the water shown in the illustration are reclining in the whale's mouth, directly against the baleen, which looks like a polar bear's skin. It is anything but that, for what seems to be hair is really shredded bone.

�� �