The Inventor -

William Kennish’s major achievement was the invention of the Marine theodolite which allowed his “Method for concentrating the Broadside of a Ship Of War...” to be so successfully trialled. The “Method” also included the breast-pieces and quoins to set the angle of the guns.

A method for concentrating the fire of a broadside of a ship of war

The marine theodolite

Description of the method for engaging a battery

A method for floating guns on shore by means of water tanks

Description of a fuze

On the disadvantages that attend the use of black paint on board ship – 1838

Three types of pumps – 1838

An artificial horizon – 1838

Method of drowning the magazine of a ship of war – 1838

A pneumatic sounding instrument 1838

Fuze – 1838

Hydrostatic diving machine – 1838

Improvements in steam engines – 1838

The pneumatic tube – a letter to the admiralty – 1845

William’s propeller – 1845

Linking the Calf, Thousla and Kitterland to the Manx mainland – c.1846

A harbour of refuge in the isle of man… (c. 1846)

Sea water desalination equipment – the “pneumatic invigorator” 1848

United states patent 7,023 of January 14 1850 – Hydraulic Engine

River bed diving bell – Brooklyn Harbour June 1850

Dredger/Submarine Excavator US Patent 17,306 - 1857

Clearing the beds of Rivers - UK Patent 2409 - 1859

Articles in the American Railway Review of 1859

Rotary Hydraulic Motor UK and US patents of 1860 & 1861.


The marine theodolite (above, top of figure) is aligned with the opponent ship’s waterline; the range is then called out and the gunners set the Quoin elevation according to the deck and the range.

To aim the guns to a single point at this elevation, each gun had a Breast-Piece with uniquely drilled sets of alignment holes into which a pair of pins can be dropped in to fix the range at 300, 400 or 500 yards:


The marine theodolite was mounted on a gimbal and had a counter-weight to ensure the elevation sight will always be accurate irrespective of the roll of the vessel; if the elevation is set as the ship passes through vertical and the same point is used to ring the linked deck bells to signal firing, the range and targeting will be accurately reproduced.

The target sighting tube T was adjusted so that the target  ship could be seen through it when the counterbalance weight B was located vertically. Adjuster A moved the ball and arm B along it, varying its inclination.  Alignment sight C was then lined up with T at the correct position, which would happen every time B became vertical.  This would allow the gun commander   (typically the captain) to issue range instructions to the guns; they would set breast-pieces and quoins accordingly. When the ship rolled to the vertical position, C would line up with T and the command to fire would be given - pulling sharply on a rope linked to bells positioned on each gun deck. The guns would then issue a salvo directed to a single point.

Family history recounts also that William was involved or associated shortly before his death in 1862 with the development of USS Monitor - the first Turreted gun ship. Currently no independent written records have been located to verify this very interesting story!


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