THE WORLD'S ADVANCE 



81 



To Remove Scratches from Hard 

 Rubber 



Shallow scratches or engraving can be 

 obliterated from the surface of India 

 rubber by passing a heated soldering cop- 

 per over a thickness of paper which is 

 superposed upon the surface of the rub- 

 ber. 



Contributed by 



P. J. HOFFMAN. 



Filling Foundation Trenches 



When building foundations it is some- 

 times difficult to reach the forms after 

 they have been put in place, in order to 

 pour in the concrete. The problem can 

 be solved by an arrangement similar to 

 that shown in the illustration, which can 

 be erected with materials usually avail- 

 able about the house, and without the use 

 of special tools. 



A simple plan is to bolt two pieces 

 of iron strip on a board and slip their 

 lower ends into the form where they are 

 bent back, so that the board slopes out- 



wards at an angle of about 4.5 degrees. 

 A piece of wood or other material fas- 

 tened to the middle of the board on the 

 outside has its free end on the ground, 

 thus holding the board in the proper 

 position. 



The concrete poured on this board will 

 slide down into the form without the 

 least trouble. 



Contributed by 



MARGARET W. MOODY. 



Automatic Door for Chicken Coop 



To obviate the unpleasant necessity of 

 arising too early to open the door of the 

 chicken coop and let the poultry into the 

 yard, an automatically opening door can 

 be easily made according to the design 

 suggested in the accompanying sketch. 



The first step in the work is to pro- 

 vide a hinged platform inside the chicken 

 coop under which is placed a 

 spiral spring of just enough 

 strength to give away under the 

 weight of a hen. A door is next 

 made and hinged at the top as 

 shown. To this door is fastened 

 a rope leading to a weight that 

 is heavy enough to lift the door. 

 A small strip of wood is nailed 

 across the front of the hinged 

 platform, completing the work. 

 The details are clearly shown in 

 the sketch and require no fur- 

 ther explanation. 



The action of the automatic 

 door is quite simple. As a hen 

 steps on the platform the strip 

 at the front end is pressed downward, 

 releasing the door, which flies open be- 

 cause of the weight attached to it. 

 Contributed by 



E. I. BRADSHAW. 



Have you any ideas for this depart- 

 ment? Why not send them in? Ideas 

 are paid for at space rates when pub- 

 lished in these columns. 



