Appleton's dictionary of machines, mechanics, engine-work, and engineering : illustrated with four thousand engravings on wood ; in two volumes (1873)
D. Appleton and Company · New York : D. Appleton and Co. · leaf 618
l. In the ends of threeof these flaps are small holes, each one a little different in size, so that when folded the smallest holeis the lowest, and the largest the third in the layers, whilst the fourth is blank, the wax belowwhich not only secures all the flaps, but adheres also to the enclosure.… … The ordinary four-cornered envelop, fitted to form what M. Remond calls the Detector, appears toanswer all the requisites of security and elegance. The sealing-flap is embossed with some device, thecentre of which is perforated in any ornamental way, and a colored wafer is placed beneath it,…
Mechanical engineering · Mechanics · Engineering
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