Popular Science Monthly 



This Bird's Nest Is Evidently 

 a Two -Room Apartment 



BIRDS, like persons, sometimes do 

 strange things. Here is a double nest 

 of a "Chipping" sparrow, an un- 

 usual type indeed for this 

 bird. A guess at the ex 

 planation would be that 

 a roving bird, probably 

 a cuckoo, which is 

 notoriously lazy and 

 homeless, deposited an 

 egg in the sparrow's 

 nest while she was 

 taking a bit of recrea- 

 tion. When the spar- 

 rows discovered it they 

 busied themselves 

 making an addition to 

 the original nest, to 

 which they transferred 

 their own eggs, leaving the intruder's in 

 the old nest to addle. 



A freak nest built by a pair of sparrows 

 probably because of a strange egg 

 laid by another bird in the original nest 



525 



curious vehicle which plunges through the 

 waves as easily as any boat and which runs 

 on land as easily as any automobile; for 

 Delia is both boat and car. 



Now comes M. J. Ravaillier, a French 

 inventor, with a smaller vessel of 

 similar design. The accom- 

 panying photographs show 

 this boat on land and 

 emerging from the 

 Seine. It measures 

 about sixteen and one- 

 half feet in length and 

 seats four persons. 

 Its steel hull is sup- 

 ported in front and 

 rear by the usual axle 

 and wheels. The axles 

 fit into watertight 

 tubes which pass 

 through the hull. The 

 craft is propelled by a 

 twelve-horsepower engine. Two distinct 

 transmissions are used. 



Which Is It— Boat or Motor Car? It 

 Travels on Both Land and Water 



"T~\ELIA the motor duck" is no doubt 

 J_y remembered by readers of the Popu- 

 lar Science Monthly. For the benefit of 

 those who did not see her in our issue of 

 March, 1916, let it be said that Delia is a 



The boat is 

 hauled up out 

 of the water 

 with ropes. 

 After which it 

 proceeds over 

 the land route 

 with a chauf- 

 feur at the 

 driving wheel 



It Takes About 150 Pounds Pressure 

 to Break an Egg 



NATURE executed a wonderful piece of 

 workmanship when she put the shell 

 around the egg. Most of us have an idea 

 that the shell is fragile. It is — sometimes; 

 but scientists have established the fact that 

 the average pressure under 

 which white eggs break is 

 one hundred and twelve 

 pounds. Strange to say, 

 brown eggs are stronger 

 than white ones. It takes a 

 pressure averaging one hun- 

 dred and fifty-five pounds to 

 break them, the minimum 

 being one hundred and 

 twenty-five pounds and the 

 maximum one hundred and 

 seventy-five pounds. When 

 it is considered 

 that the thick- 

 ness of an aver- 

 age eggshell is 

 .013 and the di- 

 ameter of the 

 eggs one and 

 three-quarter 

 inches, some 

 idea may be 

 formed of their 

 enormous 

 resistance. 



