If you have lenses you are not using, emulate 

 the example of this man and enlist them in the 

 army. The officer shown in the picture above 

 is Captain Dawson, who used to make photo- 

 graphs for the "Popular Science Monthly" 



Have You a Camera Lens? Enlist 

 It in the Army 



THE Signal Corps of the Army needs 

 lenses for cameras to be used by the 

 fleet of observation airplanes now being 

 built. If you have a lens of the required 

 type, do your bit by enlisting it in the 

 service of the Army. Write to the 

 photographic division of the Signal Corps, 

 U. S. A., Mills Building Annex, Washing- 

 ton, D. C, stating what you have on 

 hand and what price you want. 



Because the camera lens is 

 the eye of the Army 

 and because German 

 lenses can no longer 

 be bought, a 

 serious situa- 

 tion has arisen. 

 The Bureau of 

 Standards, of 

 the Depart- 

 ment of Com- 

 merce is now 

 perfecting a 

 substitute for 

 the German 

 "crown bari- 

 um" glass. 



Popular Science Monthly 



1,1 IS Hi «. _^ A Battleship Made of Stone — A 



Landlubber's Feat 



/XLTHOUGH four months of his 

 Ix vacation went into the building 

 of a stone battleship, John von 

 Wiegand of Brooklyn, N. Y., is proud 

 of the monument which tops a little 

 hill of broken rock, overlooking a stone 

 quarry at Haines Falls, N. Y., in the 

 heart of the Catskill Mountains. 



Mr. von Wiegand is a retired police 

 inspector, having passed the age limit 

 of the service. A little over a year ago 

 he spent his vacation in the Catskills 

 and conceived a plan for building a 

 structure out of stone. His choice 

 settled on a battleship. 



A number of boys, seeking some 

 form of diversion, soon became inter- 

 ested in Mr. von Wiegand's plan. 

 To each one he gave a time card on 

 which was kept an accurate record of 

 the working hours. So, aided by his 

 staff of juvenile engineers, the former 

 police inspector constructed his battle- 

 ship step by step. 



The ship measures twenty-eight feet in 

 length and eight feet in beam. It is built 

 entirely of flat stone slabs of varying sizes 

 and shapes. The funnels consist of short 

 lengths of tree trunk, with the bark left 

 on. The masts are merely young trees 

 with the branches stripped. The decks 

 and roof of the superstructure are of large 

 flat slabs of rock, such as are used for 

 sidewalks, while the turrets are shaped 

 with curved stones and armed with 

 "guns" made of young tree trunks, 

 stripped of branches and bark. No 

 cement or mortar has been 

 used for holding the 

 stones together, 

 since the weight of 

 these compo- 

 nents is suffi- 

 cient to keep 

 them in place. 

 In the vitals 

 of the battle- 

 ship has been 

 placed a bottle 

 containing a 

 record of 

 the names 

 of the con- 

 structors. 



A battleship twenty eigj 

 flat slabs of stone. The 



it feet long, which is built of 

 funnels are short tree trunks 



