THE WORLD'S ADVANCE 



355 



grains of ammonium nitrate in two 

 ounces of alcohol. The solution should 

 be put into a slender bottle, over the 

 mouth of which is stretched a diaphragm 

 of thin rubber punched with a tiny hole. 

 During fair weather the liquid wfll re- 

 main clear, with the solid particles set- 

 tled close to the bottom. If a high wind 

 is coming, the liquid will take on the 

 appearance of fermentation, a film of 

 solid particles spreading over the surface. 

 The approach of rain is signaled by the 

 formation of crystals throughout the so- 

 lution. 



Contributed by 



GEORGE W. GREENE. 



Making Sash Weights Heavier 



The author experienced trouble with 

 his windows which would not stay up 

 because the weights were too light. After 

 determining how much additional weight 

 was needed, the weights were taken out, 

 cord and all, exercising the precaution of 

 drawing in a thread for pulling the cord 

 back. Some heavy wrapping paper was 

 then wrapped around the head of each 

 weight, tied tightly in place and melted 



lead poured in. This flowed around the 

 cord and head of the weight, making a 

 neat job. 



Contributed by 



WM. C. HOUGHTON. 



A Safety Lock for Hook on Screen 

 Door 



A simple safety lock for the ordinary 

 hooks used on screen doors can be made 

 from a block of wood half an inch thick, 



two inches high and one inch wide. The 

 corners are cut off so as to give it the 

 shape shown in the illustration. A hole 

 is then bored in one end so that it may 

 be fastened in place. The other end is 

 cut off in order that it will cover the 

 hole of the eye. 



The block of wood is then screwed 

 over the eye sufficiently tight so that it 

 will remain in whatever position it is 

 placed. The action of the lock can be 

 easily understood by studying the draw- 

 ing. 



Contributed by 



THOMAS SHEEHAN. 



To Moisten Fingers Without Chapping 



In order to prevent the chapping of 

 the fingers of clerks who are compelled 

 to use finger moisteners continually, an 

 army surgeon has suggested that a small 

 amount of glycerine be poured into the 

 container of the moistener with the 

 water. 



Contributed by 



CHARLES M. STEWART. 



