The Rev. T. R. Robinson's Description of an improved Anemometer. 1 75 



bar slides in a dovetail on the front plate, and carries adjustable tubes at its 

 extremities, in which pencil-holders are placed, and made to act by weights 

 placed in their cups. Since, however, in the direction-register, the pencil, as at 

 first arranged, and shown in the figures, travels from the circumference, I have 

 found that in damp weather it occasionally has pulled the paper from the clips 

 and torn it. I have, therefore, lately carried it by an additional piece, one end 

 running in a guide at 0, the other provided with a stud Avhich fits in p' : this 

 complicates it a little, but remedies the inconvenience, and makes the time- 

 reading the same in both registers. 



The paper used is printed in red, from a plate engraved with a graduation 

 of degrees and half degrees. Within this are a series of concentric circles, 

 which represent portions of time. Those which correspond to hours are 

 stronger than the rest, and half an inch apart ; the intermediates show decimals 

 of the hour. The mode of using it is this : the pencil p' being removed, the 

 date is written on P near its pencil ; the clock is then wound up, and p draws 

 a line fi'om the circumference to the centre. The paper on P' is then removed 

 or shifted, and if another be placed, it is similarly dated, with the addition of 

 the degree, which is set at the fiducial line ; and the pencil p' is replaced. 

 Then, during the ensuing twelve hours, the action of the clock carries the 

 pencils from the centre to the circumference. If there were no wind they 

 would merely draw radial lines ; but in general p traces a spiral, and p' shades 

 an irregular sector. The clock should be adjusted so that the twelve hour 

 circles should be exactly traversed. In general, a space-paper may contain 

 four or six spirals, dating each winding line ; and a direction one, two, or three 

 sectors, shifting the zero point for each. This zero in my practice repre- 

 sents a wind from the south, and the Graduation goes round from west to north. 

 The papers are finally fixed with a weak solution of mastic in common whiskey, 

 and preserved for reference. 



In reducing these diagrams to a form available for computation, I have 

 found no system preferable to the method pointed out by Dr. Whewell in his 

 memoir. In the first instance, the centres of the papers are restored ; in the 

 space-papers, drawing radii through the intersections of the spirals with the 

 hour-circles, the graduation gives the hourly spaces, which, if necessary, are 

 corrected for friction : these are tabulated. In a second column is entered the 



