... slats at the ends, and the nail heads were then filed off so that the projecting ends formed trunnions for the slats to turn on. The slats were linked to a connecting rod with double point tacks. A small double point tack was driven into the upper edge of each slat about 1/2 inch from the right hand end. Then through each of these tacks we hooked a second double point tack and drove it into the rod. The tacks on the rod were placed just 2 inches apart. A substantial frame was then made of 3/4-inch stuff 1-1/2 inches wide. The frame was square, with an opening ... — The Scientific American Boy - The Camp at Willow Clump Island • A. Russell Bond
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