Description

This instrument consists of three parts: a distance register, kept aboard the ship; a tow rope; and a rotator, towed behind the vessel. The distance register is a bronze cylinder containing calibrated gears. It has three dials behind a glass pane, which recorded the ship’s progress in eighths, miles, and tens of miles. The rotator, or spinner, is a pointed brass tube with four long, twisting fins. The towrope, made of braided cotton, is protected from chafe by a leather and twine patch where it joins the rotator.

Taffrail logs were an essential part of navigation at sea before electronic aids were developed and were used to measure how far a ship traveled through the water. Patent logs like this one were a major improvement on earlier models because they recorded continuously, giving a more accurate picture of a ship’s progress. The technology was developed by Truman Hotchkiss, a Connecticut sea captain, in the 1860s. John Bliss & Co., prominent nautical instrument makers, purchased Hotchkiss’s patent and regularly added their own improvements to it.

Lettering above the dials reads: "John Bliss & Co Taffrail Log Patented June 6, 1876 / Sep. 17 1878 / Apr. 8 1884 / July 21, 1885"

Type

label

Location

front

Text

John Bliss & Co. Taffrail Log Patented June 6, 1876 Sep. 17 1878 Apr. 8 1884 July 21, 1885