Projectors and Slides
A. Projectors
   "The [picture at the right] represents one of the improved phantasmagoria lanterns; a tin box fifteen inches high, ten long, and seven and a half wide, having two double convex lenses mounted in a brass cell, and kept in by a counter screw and slip [sic] into a short tube soldered inside the lantern; the painting is slid in a aperture close to the two lenses and is kept in place by a heliacel spring." (From the 1854 edition of Pike's Illustrated Descriptive Catalogue of Optical, Mathematical, and Philosophical Instruments, published in New York City)

   This projector is in the collection of the National Museum of American History of the Smithsonian Institution, and has been repainted. Depending on the lens (3" to 4"), the cost was $14.00 to $18.00.

   The light source was a small lamp with a reflector behind it. The chimney produced a draft and allowed the hot air to escape; the kink in the chimney kept stray light from escaping.

   The projector at the left is in the Garland Collection of Classic Physics Apparatus at Vanderbilt University. The light source is an arc light that was probably made by Gaertner of Chicago, and thus dates from the first quarter of the twentieth century. The carbon rods acting as electrodes from the arc are missing. 

   An arc lamp operates at a high temperature, and so there is a good distance between the light source and the slot for the slide carrier. 

   This is one of a line of projection lanterns made by Queen of Philadelphia, and is probably the "Excelsior" model priced at $60 in the 1889 Queen Optical Lantern Catalogue. It is missing the tall stack shown in the catalogue cut. Note that the walnut body is separated from the metallic inner box to protect it from the high temperatures of the three hundred candlepower petroleum, double-wick lamp. 
   The projector is in the Wileman Collection at the North Carolina School of Science and Mathematics in Durham.
   The slide projector at the left is in the Museum at St. Patrick's College, Maynooth, County Kildare, Ireland. 
   The magnificent Leybold Universal Projection Lantern at the left, shown with a full set of accessories, is in the Jack Judson Collection at the Magic Lantern Museum in San Antonio, Texas. 

   Accessories include the  polariscope on the right hand side, the projection galvanometer just right of center, Newton's rings in the foreground and Lloyd's mirror upright just left of center,

   The lovely lantern slide projector at the right is in the Jack Judson Collection at the Magic Lantern Collection in San Antonio, Texas.

   The projector was made by George Wale & Co., "Philosophical Instrument Maker to the Stevens Institute of Technology, Hoboken, New Jersey".

   Underneath, and to the rear, can be seen the connections to the oxygen and acetylene supplies. The burning mixture played on a block of lime , producing an immensely bright, white light.  

 This projector is designed for projecting film strips, and is in the Wileman Collection at the North Carolina School of Science and Mathematics in Durham. 

   Its light-weight construction suggests that it borders on being a toy

B. Slides
   The typical nineteenth century slide was 3 inches in diameter and mounted in a mahogany block 7 inches by 4 inches by 3/8 inch thick. The glass was held in place by a wire snap ring. 

   The slide at the left shows the shore end of the Giant's Causeway at Bushmills in County Antrim, Northern Ireland.  Here, slowly cooling lava produced a series of basalt columns with five, six or seven sides. The majority of the columns are vertical, and since the columns always grow at right angles to the cooling surface, it appears that the lava must have formed a fairly flat surface. The formation runs across the Irish Sea to Fingal’s Cave on the Island of Staffa, giving rise to the legend that the causeway was built by the Irish giant Finn McCool to enable him to travel dry-shod to Scotland. This may be true.

   The slide is in the Museum at St. Patrick's College, Maynooth, County Kildare, Ireland. 

   The slide at the right below in the Harvard Collection shows the phenomenon of atmospheric refraction known as looming. The example at the left from St. Patrick's College in Maynooth clearly uses Ireland as a reference point.
            St. Patrick's College, Maynooth, Ireland                                               Harvard University
   These mechanical slides have little to do with physics. They are, however, quite beautiful and fascinating to watch as the crank is turned and projected patterns change. 

   The upper and middle slides have disks that contra-rotate, with one disk being driven by a direct belt, and the other by a crossed belt. The upper one is in the museum of St. Patrick's College in Maynooth, Ireland; the lower one is in the Wileman Collection of the North Carolina School of Science and Mathematics in Durham. 

   The lower slide, from the Wileman Collection, uses a gear drive. 

   These slides are based on photographic images that are then hand-colored. 

   These devices have the same appeal as  harmonographs, devices to compound two or more simple harmonic motions at right angles to each other. 

   The hand belongs to Jack Judson, whose magnificent collection of projection lanterns, optical devices and physics apparatus I visited in January 2003 at the Magic Lantern Collection in San Antonio, Texas. 

   This is an orrery slide for a projection lantern; as the crank is turned, the planets revolve at varying rates controlled by the gearing) around the sun.

C. Overhead Projector
  The nineteenth century name for the overhead projector was the Vertical Lantern. The light source was a separate lantern whose parallel light beam was trained on the lower diagonal mirror. A second diagonal mirror at the top sent the light horizontally once more. The object was placed on top of the stage, under which was a large converging lens. The image was formed by a lens placed after the second diagonal mirror. A modern overhead projector uses a Fresnel lens under the object, and because it is cheap and easy to make a large lens of this type the stage can be relatively large. 

   The device was first shown in the United States by Henry Morton, the President of the Stevens Institute of Technology. However, it was also developed by Edmund Becquerel in 1853 and first shown by Jules Duboscq of Paris in 1866. (Debbie D. Griggs, "Projection Apparatus for Science in Late Nineteenth Century America", Rittenhouse, 7, 9-15 (1992) and the 1885 Duboscq catalogue)

   The apparatus at the left was made by Duboscq and purchased by Vanderbilt University ca. 1875. It is listed in the 1885 Duboscq catalogue at 250 francs. The right-hand apparatus was also made by Duboscq and is at Yale University

   The vertical projector at the left is in the apparatus collection of the University of Cincinnati. The side of the round, black base holding the lower diagonal mirror is marked "Man. Jules Duboscq/Ph. Pellin/Paris."

   The Pellin catalogue, ca. 1900, shows this apparatus with an attachment to demonstrate the propagation of waves. 

   The photograph is by Kelly Peller.

Sometimes all you find is the lens of a projector or a camera, like this example at Kenyon College, with its brass mount and its morocco leather lens cap.

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