The Largest Telescope on This Side of the Atlantic – 1838

By Ernst E. Both

From the November – December, 1975 issue of The Spectrum, a publication of the Buffalo Astronomical Association.

Apparently the only reflectors made in America at that time (other than amateur efforts), were those of the Herschelian type (where the image is viewed at the corner of the front end) made and sold by Amasa Holcomb (1787-1875), a self-taught pioneer who started to make reflectors around 1826 and began selling these commercially around 1830. A price list of his reflectors available in 1842 includes these:  

 
We have the following testimony by E.P. Mason of the performance of a 6½-inch Holcomb reflector:

"With the instrument referred to (6½-inch, 7½-ft. Herschelian), xi Librae and zeta Bootis have been often and easily separated, and zeta Cancri well elongated. A rare night early in 1838, showed gamma Virginis and lambda Ophiuchi notched on either side, pi Aquilae was pronounced a very easy star, and Saturn's ring was seen double nearly throughout its visible portion.36 Andromedae is also within the reach of the instrument ...and since on referring to European observations, we find that few or none of their telescopes of equal focal length are competent to resolve closer test- objects than these, we are thus enabled to decide on the great excellence of Mr. Holcomb's instrument."

But to return to the "largest telescope." Guided by Mudge's "Treatise on Making Speculums for Telescopes" (a book unknown to me; remember the mirrors of those days were still made of speculum metal), Smith and Mason first tried their hands on a six-inch reflector. Their experiences are reported by Denison Olmsted (1791-1859), Professor of Natural Philosophy and Astronomy at Yale College:

"They procured the raw materials, obtained a mould, and did their casting in their anthracite stove, protracting their labors to a late hour of the night, after the lessons of the day were completed. Re-melting their first compound and pouring it into the mould, they were so fortunate as to produce an excellent cast. In about a week, by employing every moment of time they could get, and laboring alternately, they succeeded in making their tools, and in grinding down the rough casting. They next procured a hone, cemented it to a block of wood, and turned it to the proper shape to fit the gauges, and with this commenced giving their speculum the requisite figure. 'At length (says Mr. Smith) the momentous time arrived for the polishing. With a degree of trouble and caution we often laughed at afterwards, we formed the polisher of pitch, and set it aside to cool. We were obliged to work chiefly by night, as our college studies required our unremitted efforts during the day. After a hasty supper, therefore, we commenced the labor of polishing. The polishing powder used was the red oxide of iron, and so cautious had we been, that we had sent to New York with directions to procure the finest article at any expense, and we were fortunate in obtaining it. I scarcely need say that we afterwards prepared it for ourselves, and finally laid it aside for putty, or the combined oxides of tin and lead. As the figure of the pitch polisher had altered somewhat in casting, we commenced polishing the metal in the centre first. We worked alternately from six to ten o'clock, and although the speculum was in part brilliantly polished, it was still almost one fourth of an inch from the edge. This was carefully watched, often measuring it to see how fast we were gaining upon it. Mason and my brother, while I wrought, were stationed on each side of the polisher, all ready, when it became dry and stuck, to breathe upon it and moisten it.' ” 

The 25-foot reflector of Greenwich Observatory by Ramage. 
The mounting is very similar to that used by Smith and Mason 
in their 12-inch reflector.

In the summer of 1838 they proceeded with the construction of the 12-inch. Mason describes the telescope as follows:

"The telescope ...was of the Herschelian construction, with an aperture of twelve inches and a focal length of fourteen feet…although much inferior in size and light to some of the gigantic reflectors of the Herschels, it is yet entitled to some distinction as the largest telescope on this side of the Atlantic.... A tolerably good metal was cast, after several failures, and the speculum was finally polished near the close of the summer. Mr. Smith and Mr. Bradley shared the expenses attending the formation of the mirror and erection of the telescope, and divided the long labor of grinding the speculum, and I united with them in the less tedious task of giving the mirror its final polish and figure...it has since been frequently and perseveringly repolished by Messrs. Smith and Bradley. ..The mode of mounting the telescope was similar to Ramage's, but ruder. The base consisted of three beams, forming a triangle, which revolved on a circular ledge of plank, by means of rollers at the angles, and which was guided truly in its circuit by a cross-piece, through which rose a central bolt, firmly driven into the ground. From the angles of this base rose three beams, meeting at a height of sixteen or seventeen feet from the ground, and a rope passed through a pulley fixed at this height, and sustained the weight of the upper part of the telescope. The lower end, containing the speculum, rested on a small platform at one of the solid angles of the base, and revolved with the frame. The quick motion in altitude was by means of the rope just mentioned, which passed down to a windlass at the base, while a slow motion was gained by an apparatus very similar to that described and figured in Pearson's Astronomy attached to Ramage's telescope - a combination of ropes within the immediate command of the observer. In azimuth the whole frame could be wheeled about by a single person, and a slower motion was obtained by simply swinging the telescope by the hand, which could be done by the observer, in following a star, with perfect steadiness. At very high altitudes, the system of ropes was not available; but the weight of the upper end of the telescope was then so little that the observer could grasp the tube in its arms, steadying them by contact with the converging beams, and carry on his work nearly as well as before. This method of directing a large telescope is much ruder in description than in practice. A light frame-work of steps, detached from the main frame, served to support the observer in his elevated situation. Against this the tube of the telescope could be steadied at any moderate elevation, by means of a simple contrivance; this, however, was never necessary unless in high winds. The tube was, at first, of wood, but was afterwards replaced by sheet‑iron, on account of its superior lightness and portability; it was painted outside and inside, and protected, during bad weather, by oil-cloth, the speculum at such times being taken out."

The telescope was used by Mason in 1839 to make excellent drawings of nebulae, especially M20 and M8 (Trifid and Lagoon), M17 (Horseshoe), and NGC 6992-5 (part of the Cygnus Loop).The telescope was dismantled in August of 1839 and upon graduation of Smith, taken home with him to Ohio City, Ohio, where it was remounted. Mason died of tuberculosis in December of 1840.

In Ohio City, the telescope was given a better frame:

"The stand is precisely similar to the engraving, in the Philosophical Transactions, of the one erected by Ramage at the Royal Observatory, Greenwich. It is full twenty feet high, and has a sliding gallery that will hold, with convenience, four persons. The telescope swings between two parallel beams, about six feet apart; up and down these the gallery can be raised or depressed by one person easily. The telescope is constructed to roll forward, so that the mouth may be at a convenient distance from the gallery. After observing, the tube can be let down into a tight box, and locked up; the whole is supported by four iron rollers, and can be turned by one person in any direction. The apparatus for slow motion in altitude is the same as in New Haven; I have been making some arrangements for slow motion in azimuth."

To this account (from a letter by Smith to Mason) Mason added: "From his (Smith's) zeal and activity, with so valuable an instrument, we cannot but expect the most interesting results." Apparently however, these results did not materialize and I do not know the eventual fate of the 12-inch.

Upon his graduation from Yale College, Mason remained there as a resident graduate, working on a book, Introduction to Practical Astronomy, designed as a Supplement to Olmsted's Astronomy. Unfortunately Mason died in his 22nd year, on December 26, 1840, one year before this book appeared in print. Earlier in 1840 Mason had published "Observations on Nebulae with a Fourteen Feet Reflector, made by H. L. Smith and E. P. Mason, during the year 1839" (in: Transactions of the American Philosophical Society, vol. 7, N.S., p. 165-213). It is evident from this paper that Mason was the primary driving force behind the building of the "large telescope" and that he performed most of the observations. These indicate that he was a very excellent observer whose premature death probably robbed American astronomy a man of great promise. (Note: Information presented here is based on the two works by Mason mentioned above, and on Olmsted's book: Life and Writings of Ebenezer Porter Mason, 1842.)