The original organ in the present edifice was built in 1842, allegedly by Henry Erben of New York City, and installed in the rear gallery. However, according to the American Musical Directory of 1861, this organ had "2 banks keys, 20 stops, 2 octaves pedals" and was "Built by Thomas Hall, in 1842." In the Hall & Labagh Ledger the specifications of the organ are transcribed twice, so it seems quite possible that the organ was in fact built by Thomas Hall.

A description and specification of the this organ appeared in The New York Herald (Aug. 11, 1842):

"THE NEW ORGAN in the elegant church of Ascension, corner of Fifth Avenue and Tenth street, was publicly exhibited yesterday afternoon to a large concourse of ladies, gentlemen, amateurs and laymen. It was constructed by Henry Erben, the organ builder of this city, whose reputation and works extend throughout all our populous towns. The front of this magnificent instrument is finished in black walnut, to correspond with other parts of the church, the appearance of which would be materially improved, however, by reducing the height of the railing around the enclosure that encompasses the choir. While present, "God save the King," with variations, was elegantly played by Mr. Alpers, and "Hail Columbia" by Harrison. Mr. Timms also gave some specimens of his execution, which combined, presented the powers of the noble instrument to the audience, which appeared highly gratified.

"The full notes of the trumpet and dulcet tones of the flute were remarked as quite superior. The peculiarities of this instrument are, that the swell runs the whole gamut of the keys. The large pedal stop is 16 feet in height, with 37 pipes. It also has two sets of finger keys, one set of pedal keys, three composition pedals, with two couplers, one of which connects the great organ and swell, and one the octaves. Another connects the pedal and great organ, and a fourth the pedal and swell. The great organ contains the following stops: [see below]

"The cost of the instrument is $3,500.

"The seat of the organist, with the keys and stops, are thrown forward of the instrument in such a manner as to allow him to sit upright instead of the customary leaning position, which is a valuable improvement in its construction. The performance of the organ was such as gave full satisfaction to all who witnessed it."

Replaced a 1830 Erben after that was destroyed by a fire. Identified through a brochure published by Henry Erben c. 1874; replaced in 1884 by 2/24 Hilborne L. Roosevelt Op. 129.