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made models of boats with various forms of screw, which worked 
successfully. He himself considered that the first idea of the screw 
propeller had occurred to him as a mere child ; his first model was- 
that of a ship 2J feet long, and a drawing which he published of 
it in later life shows a very good four-bladed screw propeller ; he 
attempted unsuccessfully to drive this by a windmill on the boat. 
In 1821, after seeing the “Tourist” paddle steamer, he made some 
further experiments, but having to leave the sea coast he dropped 
the subject. In 1825 he returned to Dunbar, and again attacked 
the problem, trying first four blades, then three, and then two, driven 
by the main-spring of a clock. At first the screw was placed in 
front of the rudder, and the sketches since published by Mr Wilson 
show the exact arrangement now usually adopted. He abandoned 
this plan, however, in consequence of leakage at the stern tube ; and 
in order to get the opening above water line he used two single 
blade right and left propellers immersed for less than half their 
diameter and driven in opposite directions, being placed one behind 
the other, and connected by bevel wheels. 
In 1827 young Wilson was introduced to the Earl of Lauderdale, 
whose son saw a small boat about 3 feet being driven in this way. 
Lord Lauderdale appears to have brought the matter to the notice 
of the Admiralty, but the young inventor met with no encourage- 
ment in official quarters. He next exhibited his model before the 
Dunbar Mechanics’ Institution. A record of the exhibition was 
made in the minutes of the institution for October 18, 1827 ; and 
the Edinburgh Mercury of the 29th December 1827 alludes to the 
invention. The Highland Society of Scotland in 1828 appointed a 
committee, which after seeing the small model made a grant of £10, 
to enable Mr Wilson to have propellers made on a larger scale. 
Consequently a boat 25 feet long was fitted with a pair of these 
screw blades, to be driven by two men with winch handles ; the 
committee, which included two captains in the Royal Navy, reported 
very favourably on the performance of this boat, during a trip in 
Leith Roads, lasting 17 \ minutes. The model became the property 
of the Highland Society. 
In 1832 a committee of the Society of Arts reported favourably 
on the trial of another model 18 feet long, fitted with the same 
arrangement of two blades revolving in opposite directions. The 
