490 IOWA DEPARTMENT OP AGRICULTURE 



man who must spend his money carefully will find the double wall a 

 good investment. 



DOCKS AND PATENTS. 



There are two general forms of doors which may be used: the so-called 

 continuous and the individual doors. The latter are merely opening in 

 the wall 22 to 24 inches in width and 30 to 36 inches in height, spaced 

 a few feet apart vertically. The continuous door is considerably more 

 convenient. Its width is the same, but it is considerably higher, having 

 an opening from four to six feet in the clear, and these openings are 

 separated only by reinforcing bars encased in six or eight inch masonry. 

 These openings are closed by short doors so that in no case is it neces- 

 sary to pitch the silage high in removing it. 



During the past summer I have learned that certain parties were 

 threatening farmers with injunction suits, provided they proceed with the 

 building of round silos other than those licensed under the Harder Patent 

 No. 627,732, which is simply a patent en a stave silo with a continuous 

 door. There seems to be no conflict between the two, however; if there 

 were such a conflict one would still have a perfect right to build what- 

 ever kind of doors one wishes in a masonry silo, because in a rather 

 interesting search for old stave silcs over the Uni'ed States we have 

 recently found at least three dozen cases, any one of which would inval- 

 idate such a broad interpretation of this patent. Anyone making threats 

 to bring suit against a man building a masonry silo with a continuous 

 door should simply be laughed at and told to proceed. 



Up until four years ago all concrete silcs found were built with wooden 

 door frames. Forms for making concrete door frames of the right shape 

 are much cheaper than v/coden door frames and only two cf them are 

 needed v/hile half a dozen or more of the wooden frames are required. 

 In addition to the economical feature .of this the concrete door frames 

 are very much better from every consideration. Nearly all of the wooden 

 door frames permit the air to leak in between the concrete and the frame. 

 Furthermore it is only a question of time when the wooden door frames 

 will rot out. 



THE ROOF. 



The only logical type of roof is a concrete roof for a concrete silo, and 

 my experience is that the best and easiest form of roof to build is a coni- 

 cal roof of one-fourth to one-third pitrh. The roof a'ipeais more difficult 

 of construction to the average man than it really is. In reality it is a 

 very simple job. Rafters are cut to the required pitch; enough of them 

 are used so that they will not be more than six inches apart at the base; 

 curved headers of one inch lumber are placed between the rafters not 

 over 3.5 feet apart and over this is placed barn boards ripped corner ways. 



The sheeting should then be covered with woven wire. For a 16-foot 

 silo it is necessary to place the equivalent of a half-inch square bar in the 

 concrete directly over the wall. This prevents the roof from spreading 

 due to the weight of the concrete. Any scraps of reinforcing remaining 

 from the work may be cut in lengths from three to six feet and laid on 

 the woven wire reaching out to the circular steel above the walls. 



