The USPO only has the image of the mechanical drawings for this item available. In looking at the details pay particular attention to Fig. 5 showing the screw. This must have been the first usage of that style of tamper proof screw, an item commonly used today to make washroom stalls vandal proof.
http://pdfpiw.uspto.gov/.piw?Docid=0...iew+first+page
Upon further review I see that you can read the text, it is available by clicking on the selections in the left hand column.