A New and Improved Derrick

The Atlas Iron Construction Company used an advanced derrick for the American Tract Society Building which garnered attention.  I recently came across a complete description of this derrick in The Engineering Record, which included schematics and the following photograph which shows the work site "a few days after erection was begun, and showing the derrick and assembled iron-work up to the first story."

Frederick Williams (son of Henry C. Williams and an employee at Atlas Iron) wrote about this in his family history papers without mentioning the building site specifically:

"Frank [Harrison] invented a derrick, a square affair, with a mast and boom at each corner, which hoisted and put in place iron columns, beams, or girders, all four working at the same time and greatly expediting the building operations.  He did not patent this however so our rivals copied it ere long."

The derrick was designed with ease of use, simplicity and lightness in mind (it weighed a mere sixteen tons).  It was the subject of an article in the New York Times, which called it "the largest ever built in this city for handling structural steel."  It was over forty feet tall, made of iron beams and Virginia pine.  It was powered by two engines which were fixed on the ground.  The booms were between 45 and 53 feet long, and could lift nine tons each.  In addition to the four corner booms, a fifth was added to cover the area in the center of the derrick.

Atlas Iron was contracted to raise the building's structure at a rate of two stories per week.  After setting two stories in place, the derrick was hoisted by its own engines to the top of the completed framework - a process which typically took two days, but with the careful construction of this derrick it could be done in under a day.  With a work force of 50 men, they "expected to substantially complete the erection of the whole 3,000 tons of iron-work in about 90 days."

In publishing the details about the construction and use of the derrick, The Engineering Record thanks Frank Harrison for sharing his working drawings.  It seems he was glad to share his achievement with fellow engineers.

Sources:
"New Derrick For Rapid Building", New York Times, 25 November 1894, p 19.
"Erection of American Tract Society's Building, New York", The Engineering Record, vol 31, no 3, 15 December 1894, pp 44-47.
Family documents.