Sky & Telescope - USA (2019-11)

O. M. Mitchel

32 NOVEMBER 2019 • SKY & TELESCOPE

while he studied law. In 1831, he married

Louisa Clark Trask, the young widow of

a classmate. After a brief stint at Fort

Marion (Castillo de San Marcos) in St.

Augustine, Florida, he left the Army and

returned to Ohio.

Accidental Astronomer

Settling in the booming city of Cincin-

nati where opportunities seemed bound-

less, Mitchel started a law practice in

partnership with Edward D. Mansfi eld,

son of one of his West Point professors. But as Mansfi eld later

recollected, both were literary men: Mansfi eld often spent his

offi ce hours writing a book on politics while Mitchel read a

Latin text on oratory. Unsurprisingly, their law practice foun-

dered. Mansfi eld became a newspaper editor, and, in 1836,

Mitchel joined the faculty of Cincinnati College, where he

taught mathematics, civil engineering, mechanics, machin-

ery, astronomy, and French.

Around that same time, Cincinnati chartered the Little

Miami Railroad. On the side, Mitchel surveyed the prospec-

tive route. He also promoted and sold 800 shares of railroad

stock at $50 each to investors. In so doing, he learned how a

joint-stock corporation worked and how to approach pros-

pects for money — skills that would be crucial when raising

funds to found the Cincinnati Observatory.

Mitchel also joined several of fast-growing Cincinnati’s

literary, cultural, and religious groups, and in 1839–40

cofounded the Cincinnati Society for the Promotion of Useful

Knowledge. The society sponsored public lectures that imme-

diately gained attention and popularity. In late 1841, Mitchel

himself was invited to give a “course” or series of lectures on

astronomy for the winter and spring of 1842 — an invitation

that set the direction for the rest of his life.

Audacious Astronomy

Mitchel was likely exposed to astronomy in his third year at

West Point, when cadets took classes in the sciences. At that

time (1827–28), West Point used William Enfi eld’s 300-page

textbook Institutes of Natural Philosophy, Theoretical and

Experimental. Fully two-thirds of the 1824 fourth American

edition was devoted to optics and astronomy, progressing

from basic defi nitions to tables for calculating eclipses.

For his 1842 public lectures, however,

Mitchel wanted something dramatic to

hold the interest of a general audience. So

he devised an apparatus to project images

of nebulae, double stars, and comets as

“revealed by the powerful telescopes of

Europe.” (Just what Mitchel’s projection

apparatus was is nowhere detailed, but the optics section of

Enfi eld included a diagram of a magic lantern.)

Audiences were enraptured not only by Mitchel’s projected

images, but also by his captivating descriptions. Each lecture

drew bigger crowds. In April, he was invited to repeat his last

lecture at the Wesley Chapel, whose standing-room capacity

could have been as high as 3,000. There he announced an

audacious plan: to raise $7,500 for a magnifi cent telescope

by selling 300 shares of stock at $25 each. No subscription

would become binding until all 300 shares were sold. Each

share would make its purchaser a member of a proposed

astronomical society “and forever enjoy the privilege” of look-

ing through the telescope.

No one was more surprised than Mitchel himself when

he sold all 300 shares within three weeks. In May, at the fi rst

meeting of stockholders, the Cincinnati Astronomical Society

tARMY OF THE OHIO This engraving, which

shows Ormsby MacKnight Mitchel as a major

general in the Union Army, is unusual in that it

portrays him bearded instead of clean-shaven.

uHILL TOWNTop: This circa 1861 view of Cincinnati shows the city’s

hilly terrain. The lettered sites are: a) public landing; b) suburb of Fulton,

through which passed the Little Miami Railroad; c) Mount Adams with

Cincinnati Observatory; d) Walnut Hills; e) Mount Auburn; f) Vine Street

Hill; g) Mill Creek.

uGREEK REVIVAL Bottom: The original two-story building of the

Cincinnati Observatory, which was entered via a classically ornamented

portico, sat atop Mount Ida (later renamed Mount Adams). Depicted here

as it appeared in late 1846, the observatory was capped with a roll-off

roof that exposed the equatorial room to the night sky for observations. MI

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