TRANSACTIONS OF THE SECTIONS. 19 



and the tube will rise. The indications of the instrument being dependent on the 

 motion of the suspended tube, by the contrivance of a partially immersed annular 

 float surrounding its lower end, the displacement of a corresponding bulk of mer- 

 cury in the cistern compensates for the gain or loss of weight in the tube. The 

 range of the index is determined by the proportion which the area of this float 

 bears to that of the tube. The tube at the Observatory is 3 inches in diameter, and 

 the range 5^ times that of the ordinary barometer. 



On an Anemometer for the Registration of Cyclones or other Tropical Hurri- 

 canes. By A. Follett Osler, F.R.S. 



The anemometers erected in this country, though capable of registering the 

 storms of these latitudes, are not found equal to withstanding the force of a tropical 

 hurricane. To strengthen the parts sufficiently would cause them to be too ponderous : 

 the momentum obtained by so much additional matter put in rapid motion would 

 produce fallacious results. In the instrument proposed, of which models of the 

 various parts were exhibited, the pressure-plate is not exposed to the direct action 

 of the wind, but is placed in a horizontal position in a circular box, somewhat re- 

 sembling- the form of a cheese, which being edgewise to the current offers much 

 less resistance to the force of the hurricane. A long Hat aperture near the bottom 

 of the box is kept facing the wind by means of a vane, and the horizontal pressure- 

 plate, which is carried by strong springs, has an air-tight diaphragm round it con- 

 necting it with the inside of the box ; the force of the air entering by the long aper- 

 t (ilea and thus impounded in the box, is measured by the amount of motion commu- 

 nicated to the plate, and is recorded by a simple contrivance which is connected by 

 a wire with the pressure-plate, and dots off the maximum and minimum force of each 

 gust either on plain paper or, as recommended by Mr. Osier, on double sheets with 

 carbon paper between, so as to obtain duplicate records, the paper being carried for- 

 ward in the usual way by means of a clock. The trouble and uncertainty of pencils 

 for recording- the force of the wind is, by this plan of dotting, entirely removed ; 

 the point which makes the dot moves without touching the paper, and is brought 

 down by a double knee-joint to make the dot only when the maximum or minimum 

 pressure has been attained. 



The direction of the wind is at the same time recorded by connecting with the 

 vane two endless crank or bell chains, carried by two pulleys, the centres of which 

 are placed at a distance from one another equal to the range that may be desired 

 for making the record ; to these chains, which work parallel to one another, the 

 recording pencils or styles are attached : the movement is simple, and not easily 

 deranged. Mr. Osier also exhibited a model of a small portable observatory 

 arranged for this instrument ; it is circular, about seven feet high, and tapering 

 from three feet six inches in diameter at the bottom to three feet at the top, and 

 divided perpendicularly into four parts for portability. A strong iron hoop fits 

 over each end, to which iron rods are fixed as guys, stretching out in four directions 

 to iron or wood posts let firmly into the ground. The principal advantage of this 

 construction consists in its capability of being temporarily but securely fixed in any 

 situation that may be desirable for special anemometrical observations. 



On the Anomalies of our Climate. By T. L. Plant. 



In this paper the author pointed out the extremes which had come under his 

 observation m Birmingham during twenty-nine years, i. e. from 1830 to 1864. 



On the Meteorology of Birmingham. By D. Smith. 

 The results given in this paper were deduced from observations extending over 

 a period of twelve years, namely, from 1853 to 1864 inclusive, and as far as could 

 be the records thus obtained were compared with the results of the medical inspec- 

 tions of the borough. The weekly Returns of the Registrar-General of Births and 

 Deaths, and the meteorological returns of eleven large towns by Mr. Glaisher, which 

 accompany it, reveal facts of the highest interest, affording, as they do, a compari- 

 son of death-rates with temperature. But the author considered there was yet re- 



2* 



