We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
VI STORY OF THE PERFORATION GAUGE 6i and flutter in the most distressing manner, and no matter how dexterous the operator may be, and despite the excel- lence of his projector, he cannot by any means rectify or mitigate very appreciably defects arising from indifferent perforation. The contribution of imperfect perforation to unsteadi- ness in projection was recognised in the earliest days; and great technical skill was devoted to the elaboration of machines to puncture the film with scientific precision. Marvellous appliances have been produced for this pur- pose; but despite the infinite labour bestowed upon their production the possibility of error is ever present. Still, it has been reduced to infinitesimal proportions, and, given a careful operator, a film can be perforated with the holes varying not a thousandth part of an inch from the gauge. The very earliest type of perforating machine was known as the " Rotary Perforator," Paul leading the way in this, as in several other ramifications of the industry. The machine was driven by a mechanism identical with that utilised in the camera and projector; because the film had to be advanced intermittently beneath the punches, which were provided with an oscillating movement. This type of machine is shown in the illustration. Paul's first appliance has always ranked as more simple, efficient, and reliable than any other. During recent years the rotary perforator has fallen from favour, on the plea that it soon becomes imperfect in working; but such an accusation cannot fairly be brought against Paul's machine, since its designer used it con- tinuously for four years, during which time it punched millions of holes, and to-day is as correct in its work as when first used. It is impossible within the scope of this book to describe all the various types of perforation apparatus now in vogue, more especially as their interest lies mainly in highly technical details. I will content myself with describing three machines which exemplify the three most important methods of perforation. As this operation has to be carried out in the dark room