after the invention of the telescope the professional 

 astronomer resisted the innovation, but by the end of 

 the 17th century the new optical instrument was being 

 adapted to the quadrant and other instruments for 

 the precise measurement of the positions of heavenly 

 bodies in relation to the time-honored astronomical 

 coordinates. By the late 18th century telescopes were 

 found serving three relatively distinct purposes: the 

 increased magnification of the sky in general (in 

 which use Herschel's 48-inch reflector had made all 

 others obsolete) : the more precise measurement of 

 planetary and stellar positions (and, conversely, of 

 the Earth's shape) by means of the quadrant, vertical 

 circle, zenith sector, and similar instruments; and the 

 simple edification of the educated but not learned 

 classes, who wished not only to see what the astrono- 

 mer saw, but to have an instrument also useful for 

 looking occasionally at interesting objects on earth. 



Of these three purposes the second was the most 

 unimpeachably scientific. It is remarkable that 

 the earliest American-made telescopes of which we 

 have knowledge were made for this purpose and 

 not for the mere gratification of the curiosity of the 

 educated layman. These are the telescopes of the 

 remarkable Philadelphia mechanic, Da\-id Ritten- 

 house (1732-96). In an atmosphere not unlike 

 the intellectual democracy that characterized the 

 formation of the Royal Society a century earlier 

 in London, Rittenhouse began as a clockmaker and 

 ended as president of the American Philosophical 

 Society, our counterpart of tUe Royal Society, in 

 Philadelphia. He demonstrated not merely that 

 an instrument-maker was capable of being a scientist, 

 but also that the work of the instrument-maker, 

 as it had developed by the late 18th century, was 

 in itself scientific work. One of several observers 

 assigned by the Society to the observation of the 

 transit of Venus in 1769, he constructed instruments 

 of the most advanced types, apparently employing 

 European lenses, and used the instruments himself. 

 Of these, a 1%-inch refractor mounted as a transit 

 instrument stands in the hall of the Philosophical 

 Society. It is probably the oldest extant American- 

 made telescope. 



Rittenhouse made other telescopes which survive, 

 notably two zenith sectors now in the U.S. National 

 Museum of the Smithsonian Institution,^ but he 

 does not appear to have made them for commercial 

 sale. In the history of telescope-making in America 



he seems to have been something of a "sport." Not 

 only were the instruments which still grace the 

 desks of Washington, Jefferson, and others, of Euro- 

 pean manufacture, but the earliest observatories in 

 the United States (eleven between 1786 and 1840) 

 were outfitted exclusively (except for the Rittenhouse 

 observatory) with European instruments.^ In its 

 endeavor to establish a permanent observatory 

 even Rittenhouse's own Philosophical Society seems 

 to have thought exclusively in terms of instruments 

 of European manufacture. 



It must therefore have required some courage for 

 Amasa Holcomb, 43-year-old Massachusetts surveyor, 

 to approach Professor Silliman of Yale in 1830 with 

 a telescope of his own construction. In the auto- 

 biography printed here, Holcomb states that all the 

 telescopes used in this country before 1833 had been 

 obtained in Europe, and indicates that thereafter 

 "the whole market was in his hands during thirteen 

 years," a period which would fall, apparently, be- 

 tween 1833 and 1845. It should be mentioned, al- 

 though it is no conclusive negation of Holcomb's 

 claim, that the New York instrument-maker Richard 

 Patten in 1830 built a telescopic theodolite that was 

 designed by Ferdinand Hassler for use on the Wilkes 

 Expedition, and was subsequently used at the observa- 

 tory of the Navy's "Depot of Charts and Instruments" 

 in Washington.* We do not know the source of 

 Patten's lenses. 



Holcomb would appear to have succeeded as a 

 commercial maker of telescopes. He claims to have 

 sold his instruments "in almost every state in the 

 Union," and also abroad, but we know nothing 

 of what use was made of any of them. The telescope 

 he showed Professor Silliman was a refractor. 

 Another, preserved in the Smithsonian Institution,^ 

 is like Rittenhouse's 1769 instrument, a transit. But 

 Holcomb seems to have specialized in reflectors of the 

 Herschelean type, i.e., instruments, in which the 

 image is viewed through an eyepiece located at the 

 mouth of the tube. It is probably reasonable to doubt 

 that the serious astronomer of this period shared 

 Holcomb's enthusiasm for this type of difficult- 

 to-adjust instrument in the small sizes he produced 

 (10-inches is the largest reported). In 1834, 1835, 



2 U.S. National Museum catalog nos. 152078 and 152079. 



3 W. I. Milham, Early American Observatories, Williamstown, 

 Mass., Williams College, 1938. 



* Mechanics Magazine, 1830, vol. 13, pp. 114-115 and frontis- 

 piece. 



' See p. 184 for a list of Holcomb's instruments in the U.S. 

 National Museum. 



PAPER 26: THREE 19TH-CENTURY AMERICAN TELESCOPE MAKERS 



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