402 PROFESSOR H. S. HELE SHAW ON CONTINUOUS CALCULATING MACHINES. 
Note. 
(Added February 4, 1886.) 
Some months after the foregoing paper was communicated the author happened to 
read a letter, written Nov. 5, 1881, by M. Ventosa, of Madrid, and published in 
‘Nature’ (Nov, 24), in which the writer describes a proposed method of obtaining 
the N., S., E., and W. components of the wind. The method was briefly this. A 
sphere resting at one pole on a point in the periphery of a roller or disk, and in 
frictional contact at four points of its equator with four other rollers or disks, would 
(the planes of all the rollers being vertical) freely revolve upon the turning of the 
bottom roller. If the plane of the latter were always kept parallel with the direction 
of the wind, and it were turned at a rate proportional to the wind velocity, and at 
the same time the planes of the four others were placed in pairs respectively N. and S., 
E. and W., the latter would record the four corresponding components of the wind. 
M. Ventosa was led to this idea in 1878, after reading an account of Von Oettingex’s 
Integrating Anemometer, by the endeavour to obviate the sliding friction of that 
instrument. The arrangement he suggests is per se incapable of performing other 
mathematical operations than simple addition, and, in fact, is only one of the two 
necessary but distinct features of the author’s mechanism mentioned in the abstract 
of the above paper (Proc. Royal Society, 1884, p. 191). M. Ventosa, liow T ever, in his 
letter, truly says of his proposal, “ Cette transmission se fait ici par roulement sans 
glissement ” (the italics are his own), and he must be regarded as having, prior to the 
author, suggested the use of a sphere and rollers for effecting a change in the axis of 
rotation of the sphere without necessitating other than rolling contact.—H. S. H. S. 
