118 REPORT—1846. 
Osler has contrived an arrangement by which this is registered in connexion with the 
time and the direction. Meteorologists however are chiefly interested about the ve- 
locity, or rather the actual space traversed by atmospheric currents. The velocity at 
any instant can be computed from the observed pressure ; but the mean velocity for a 
given period cannot easily be derived from the mean pressure. But Whewell’s in- 
strument gives the desired result immediately, recording the space itself. As con- 
structed by him, however, it is liable to errors, which Mr. Snow Harris pointed out at 
the Plymouth meeting ; at the same time producing a series of observations which 
seemed so important to Dr. Robinson, that he endeavoured to contrive a machine which 
should perform the same office more precisely, and whose indications should have an 
invariable value. He was enabled to do this by the application of a fact which he 
learned from the late Richard Lovell Edgeworth, Esq.: if hemispherical cups be car- 
ried by horizontal arms attached to a vertical axis, with their diametral planes verti- 
cal, they constitute an effective windmill, which Dr. Robinson has found revolves with 
one-third of the wind's velocity. ‘To the bottom of the axis is attached wheelwork ac- 
tuating a revolving disc, which rotates through a degree for every mile traversed by 
the wind. A pencil moved in the direction of the radius by clockwork, at the rate of 
half an inch pet hour, traces on paper fixed on this disc the curve of space and time. 
A similar-dise connected with a powerful vane records the curve of direction and time ; 
as however such vanes (especially in high winds) are in perpetual oscillation, there 
is attached to it a regulator consisting of a small water-wheel revolving in a cistern, 
with a speed five times that of the vane. This of course obeys any slow change of 
direction without difficulty, but presents so great a resistance to any rapid shift, that 
the eddies are past before it yields. This, though not absolutely, yet in a great mea- 
sure, steadies the vane. The machine erected at the Armagh Observatory acts in a 
very satisfactory manner, moving when no air of wind can be felt, yet acting with 
perfect steadiness in severe gales, during one of which Lind’s gauge showed a pressure 
of 23 inches of water. He then explained how the daily results were to be summed 
up by resolving them according to axes of coordinates directed to the north and east, 
and illustrated the method by exhibiting the process for the first six months of the 
current year. 
On the Sailing Powers of two Yachts, built on the Wave Principle. 
By J. Purers, M.D. 
The first was built for Dr. Corrigan, of Dublin, in 1844; a small open boat 24 
feet by 6, of 33 tons, which did so well that she was able to beat everything near her 
own size, and to sail with those which exceed it in some instances as far as four 
times. She was dry in seas where they were wet, was very stiff, sure in stays, and 
steered well at all times. The secondis a yacht of 45 tons, O.M., for Samuel Hodder, 
Esq., of Ringabella; built from the drawing by Mr. Peasley, of Passage West, in 
Cork. She appears to have the following qualities: a first-rate performance, at- 
tained without sacrifice of any good quality, large accommodation, and high stability. 
She is weatherly, steady and easy, dry in the worst weather, and pitches and ascends 
less than any vessel I was ever in, She turns so sharply that no 10-ton yacht 
can do it quicker, and steers so well, scudding in a gale of wind, that notwithstand- 
ing an unbalanced state, from an injudicious shift of mast, she neither broaches to 
nor is compelled to lay to, which a companion of larger size (60 tons), and of tried 
sea qualities, was forced to do, and, in consequence, arrived from Cork to Dublin 14 
hours after the Wave-built yacht. In arace at Kingstown for the Railway Cup of 
100 guineas, in which she was matched against the best boats of the three countries, 
in a time race, including one fine yacht of 100 tons, she won—and did the course 
exactly in 4h. 22m, 58 s.—it being 46 nautic miles. Making no allowance for tack- 
ing or starting from absolute rest, the rate of this is 10} knots per hour. This is a 
great result for a principle yet in its infancy. The same vessel left Holyhead in a gale 
of wind, with storm-sails, main-sail stowed, and everything made snug ; with a reefed 
try-sail, a double-reefed fore-sail, and third jib. She lay in one stretch to the Irish 
coast, where she tacked to the southward, beating down to the Arklow light in 1] 
hours. Six persons on board, being separately questioned, agreed that the time from 
Holyhead to the Irish coast was 43 hours. Making every reasonable allowance, less 
than 50 nautic miles could not have been done; and this gives a velocity of 11 nautic 
