rate by means of a clock. On the same sheet the direction of the wind was recorded. This was done by means of a vane, and its movements were conveyed, by an ingenious contrivance, to a pencil which moved transversely upon a scale of horizontal lines representing the points of the compass. The curve thus drawn gave a continuous record of the direction of the wind. The rainfall was also recorded on the same paper. The rain was collected in a funnel, the top of which had a known area, and flowed into a vessel supported on a bent lever with a counterbalancing weight; the accumulating water caused the vessel to descend, and this movement was registered by a pencil, which produced a line on a part of the paper that was ruled with a scale of fractions of an inch. When the limit of the capacity of the counterbalanced vessel was reached, it discharged its contents automatically, and the pencil returned to the zero line.
The importance to meteorological observation of Osler's invention was at once recognised, and his pressure-plate anemometer was soon installed at Greenwich observatory (1841), the Royal Exchange, London, at Plymouth, Inverness, and Liverpool. Osler read a paper in 1837 before the British Association describing his instruments. To Dr. Robinson's cup anemometer for measuring the horizontal motion of the air Osler subsequently applied his own self-recording methods, thus obtaining records of mean hourly velocities as well as total mileage of the wind. Later the curves of pressure, direction, velocity, and rainfall in connection with time were recorded on the same sheet of paper.
As he explained in papers read before the British Association at Birmingham in 1839 and at Glasgow in 1840, Osler at the request and expense of the association soon developed his graphic contrivances. Has self-recording methods soon came into very general use.
By means of another series of monthly, quarterly, and annual and mean diurnal wind curves, he illustrated the average distribution of winds during each part of the day, and for the different seasons. Mean diurnal wind velocity curves were made to run parallel to the mean diurnal temperature curve, and on reducing the two maxima and minima to the same values they proved almost identical. Sir David Brewster [q. v.], who came independently to the same conclusion in 1840, paid high tribute to Osler's labours, and described his results respecting the phenomena and laws of the wind 'as more important than any which have been obtained since meteorology became one of the physical sciences.' Osler persistently urged a more scientific and methodical study of meteorology by the establishment of observatories in different latitudes. To the British Association at Birmingham in 1865 he described 'the horary and diurnal variations in the direction and motion of the air 'in the light of a minute comparison of his observations at Wrottesley, Liverpool, and Birmingham. Osler in further researches showed the relation of atmospheric disturbances to the great trade winds, and the effect of the earth's rotation in inducing eastern and western velocities in the northerly and southerly winds. Many other papers on his anemometer and on his meteorological investigations were printed in the reports of the association. He communicated his last paper to the meeting at Birmingham in 1886, the subject being 'The Normal Form of Clouds.'
Other interests occupied Osler's energies. After delivering three lectures on chronometry and its history at the Birmingham Philosophical Institution (Jan. 1842) he collected funds and set up a standard clock for Birmingham in front of the Institution, and on the roof equipped a transit instrument and an astronomical clock. Subsequently he altered the clock from Birmingham to Greenwich time, to which the other public clocks in Birmingham were gradually adjusted. In 1883 he presented to Birmingham a clock and bells, of the same size and model as those at the Law Courts in London, to be placed in the clock tower of the newly built municipal buildings. Craniometry also attracted Osler's attention; he devised and constructed a complete and accurate instrument for brain measurements, which gave full-sized diagrams of the exact form of the skull.
Osler was made F.R.S. in 1855. He retired from business in 1876, devoting himself thenceforth entirely to scientific pursuits. Among many speculative papers was an attempt to account for the distribution of sea and land on the earth's surface by a theory that the earth had once two satellites, one of which returned to it within geological time. He generously supported scientific and literary institutions in Birmingham. His benefactions, always anonymous, included 7500l. to the Birmingham and Midland Institute and 10,000l. for the purposes of Birmingham University.
