88 ANNUAL OF SCIENTIFIC DISCOVERT. 



of the organ is not touched, the wire is not connected and the 

 current does not pass ; but on premising down the ke}' a metallic 

 contact is formed, the electrieit}' darts aloiis:; the circuit, and the 

 electro-magnet, becoming at once excited, j^ulls down the pallet, 

 or opens the valve in the wind-chest, admitting air to the organ- 

 pij)es and with lightning speed causing them to si)eak. 



The couplers are applied and the stops drawn upon the same 

 principle. It has been stated that a more expensive and less 

 pimple arrangement has been successfully applied in Englaud and 

 France. 



THE AMERICAN STEREOSCOPE. 



The following is an abstract of a paper in the *' Philadelphia 

 Photographer " of January, 18G9, by Dr. Oliver Wendell Holmes, 

 the inventor of tiie American stereoscope : — 



♦♦ • The British Journal of Photography ' had two articles lately, 

 the first dated Oct. 16, 18G8, and the second the following week, 

 relating to the 'American Stereoscope,' as I see it is called in 

 Kngland. The figure they give in the second of tliese papers, 

 though not of the best model, yet shows that the instrument re- 

 ferred to is a copy of the one which was first made in Boston, and 

 of which I sha[)ed the primitive pattern with my own hands. 



" This simj)le stereoscope was not constructed by accident, but 

 was the carrying out of a plan to ri'duce the instrument to its 

 simplest terms. Two lenses were necessary, and a frame to hold 

 them. 1 procured two of the best quality, nnd cut a square frame 

 for them out of a solid piece of wood. A strip of wood at right 

 angles to this was re(]uired to hold the pictures. I shaped one, 

 narrow in the middle, broad at both ends ; at one end to support 

 the lenses, at the other to hold the stereographs, which were iu- 

 serti^d in slots cut with a saw at difl'erent distances. A partition 

 was necessary, which I made short, 1)ut wedge-shaped, widening 

 as it receded from the eye. A handle was indispensable, and 1 

 made a small brad-awl answer the purpose, taking care that it 

 was i)laced so far ijack as to give the proper balance to the .in- 

 strument. A hood for the eyes was needed, for comfort, at least, 

 and I fitted one, cut out of pasteboard, to my own forehead. This 

 primeval machine, parent of the multitudes I see all around me, 

 is in my left hand as I write, and I have just tried it, and Ibund it 



excellent I contrived another form of stereoscope 



like the first, but with a gilded, slanting diai)hragm with two oval 

 openings, so that the etlect was that of seeing the stereograph 

 tlirough a round window, with a golden light on it rellccted from 

 the slaniing surface of the diaphragm. This I showed also to 

 various dealers, as a form of stereoscope that might please cer- 

 tain exee])lional amateurs. Some time after showing it, I found 

 the so-called 'Bellevue' stereoscope in the market, which I had 

 good reason to consider an imperli'ct attemi)t at a reproduction of 

 the pattern I had somewhat freely exhibited. The eflcct referred 

 to, of cutting otf all the borderings of the ])icture, and throwing 

 (by means of the slanted and gilded diaphragm) a Claude Lor- 



