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.
Bausch & Lomb Optical Company Simplified Micro-Projection Apparatus There is a steadily growing tendency on the part of biology teachers to illus- trate their work as much as possible, using for this purpose the regular microscope slides. In many cases an elaborate equipment is not required, and in others the larger, more elaborate outfits cannot be purchased for lack of funds. To meet this situation we are offering a simple apparatus for micro-projection, consisting of an illuminant with equipment for use in connection with a projection microscope or the regular laboratory microscope. Our apparatus for projection of the spectrum and complementary colors can also be used with this outfit. Upon a baseboard, 10 x 36 inches, is secured one of our regular optical beds, 22 inches long, which carries the microscope or any required accessories. At one end of the baseboard is mounted a miniature, 4/4-ampere arc lamp. The sup- port of this lamp is adjustable for height by raising or lowering the post in its socket and is also provided with fine adjustment screws for horizontal as well as vertical adjustment. The lamp, which is of the 90-degree type, takes the pencil size carbons with one carbon (the positive in case of direct current) coincident with the optical axis. The carbons may be adjusted separately or together, by a single button. A 4/4-ampere, 110-volt rheostat with 15 feet of lamp cord and connecting plug is regularly included. (A rheostat for 220 volts can be supplied at additional cost.) The spherical correction of the condensing lenses used in connection with the illuminant is one of the principal points to be considered in microscopical projec- tion. We would for this reason call particular attention to the fact that we have designed an aspheric condenser of 60 mm (2 Y& inches) diameter, which is corrected for spherical aberration by grinding to non-spherical curves. This condenser is a part of the regular equipment on the outfit. By means of this correction an image of the arc is formed practically in one plane, so that a much greater percentage of the light collected from the arc may be utilized by the substage condenser than is possible with the regular spherical condensers. The focus of this aspheric lens is such that it takes in a cone of light from the arc lamp of about 60° and forms a large image of the arc, so that the full aperture of the substage condenser can be utilized. An adjustable mounting is attached to the front of the lamp housing for the condensing lens, and it should be so adjusted with relation to the arc that the arc image is formed at the diaphragm plane of the substage condenser. With this lens and the 4/4-ampere arc lamp it is possible to project microscopic specimens with approximately the same brilliancy that can be secured when using a much higher amperage in connection with a combination apparatus. The main problem in microscopical projection is to secure an arc image sufficiently large to fill the effective aperture of the substage condenser being used. We recommend the use of our Large Projection Microscope, as illus- trated in Figure 1, which is equipped with a series of substage condensers so com- puted that maximum illumination and field are secured with all objectives, from the 72 mm Micro-Tessar to the 1.9 mm oil immersion. See ‘Accessories.” 83