"submarine engineer" on Broad Street in Lower Manhattan during the 1850s. At this time, the term "submarine" referred to anything underwater, and not exclusively to diving vessels. During this time, he was involved in several engineering and technical projects. Photography An 1851 article in Scientific American magazine describes the Fair of the American Institute. One exhibit was of colored photographs by Messrs. Kroehl & Vetter, of No. 499 Broad Street. This does not necessarily mean this was Julius Kroehl. However, when Kroehl was ordered to support Union forces during the Vicksburg Campaign of 1863, he was directed to bring with him photographic equipment after spending one month being trained on their use by members of the U.S. Coast Survey in Washington, DC. His personal effects enumerated at the time of his death included photographic supplies. His proficiency in photographic uses in 1851 was possible. No works are known to have survived. New York Crystal Palace From 1852 to 1853, Kroehl was employed as an assistant engineer during the construction of the New York Crystal Palace. Several assistant engineers were employed to oversee the construction of certain parts of this exhibition hall. He was responsible for the construction of the dome, the building's central feature. For three years after, he was noted as the "engineer of the Crystal Palace." Flange forming machine Kroehl applied for a patent around March 1854 for a flange forming machine. It is described in Scientific American as an improvement in machinery for bending flanges on wrought iron beams. There is a pair of horizontal, and a pair of vertical rollers; the former pair has one roller with a face of the full depth of the beam, and the other has its face the depth of the beam minus the thickness of the flanges. The vertical rollers are both alike, and are of a width a little greater than the extreme width of the flanges. They are arranged opposite the space between the horizontal ones, and work in close contact with the sides of the roller. In order to give the flanges and their beams, a taper or an elliptic, or other curved form, the vertical rollers have flanges, whose faces bear on the edges of the flanges of the beam, and cause the said rollers to receive such a movement in the direction of their axes, and apply such a force I that direction as bends