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. 



