Object StatementEngine indicator, in box with accessories, brass / steel / timber / paper, designed by G D Kittoe, manufactured by James Munro, London, England, 1863, used by James Rorison on the SS Great Eastern
Physical DescriptionThe indicator is housed in a fitted box. Accessories include: 2 taper taps and 1 bottoming tap; indicator papers; wooden ruler and set square (both stamped J RORISON); hexagonal socket spanner and C spanner; hook for attaching string to moving engine part; small pulley (broken off the main unit); linkage for holding pen and transmitting motion to it (broken off main unit); and small wooden and glass objects of unknown use.
The general appearance of the indicator is that of a pair of concentric cylinders. Within the inner cylinder is located a piston whose motion is resisted by a spring in the upper portion of the cylinder. In use, this piston is subject to the steam pressure in the engine cylinder being tested. The spring is designed to compress if the engine cylinder pressure is above atmospheric and to extend if the engine pressure is below atmospheric. The motion of the spring is transmitted by rods that pass through slots in the inner cylinder and cause the movement of a pencil-holding mechanism, thus allowing changes in the engine cylinder pressure to be recorded on paper. The marker mechanism, which is broken but has no missing parts, can be detached from the top of the spring to allow installation of a replacement spring in order to change the sensitivity of the indicator.
The outer, shorter, cylinder is the drum for holding the indicator chart paper. It is provided with a channel in which the drum drive cord is wrapped. Below the drum is a clutch lever which engages the drum with the cord drive. In this manner, the device can be permanently attached to an engine, with the drum only being turned when an indicator diagram is being recorded. The indicator would be screwed to a boss mounted on the engine cylinder and fitted with a stop-cock to isolate the indicator when it is not in use.
MarksInscribed on top section, inside which the spring is located: G D KITTOE / Engineer and Machinist / 56 Compton Street / London E C / Manufactured by / JAs MUNRO / 4 Gibson Street / Waterloo Road S
On the reverse side is inscribed: J RORISON / 1863
The contents of the indicator's storage box include a ruler marked 7,8,9,10 units and a set square, each stamped with the name J. RORISON.
A card inside the box has the following hand-written on it: STEAM ENGINE INDICATOR / FORMERLY USED ON THE ENGINES / of / SS GREAT EASTERN / PRESENTED BY J Rorison Esq, some time chief / Engineer of the vessel