178 The Kev. T. R. Robinson's Description of an improved Anemometer. 



of the space, direction, and time at one view. This might in some degree be per- 

 formed by a delineation of the actual trajectory of the wind, either drawn by 

 itself, or laid down from the co-ordinates w and s, on which the corresponding 

 times are marked ; but the analogy of curves described on a plane, and expressing 

 the relation between two variables, naturally leads to the notion of a sohd whose 

 three dimensions would afford a triple representation. It would involve the 

 construction of a model, or at least a contoured plan. For, in fact, if we con- 

 ceive perpendiculars to be raised on one of my direction-papers, at each point of 

 the shading, proportioned to the velocity at the corresponding instant, their 

 totality would be limited by a relieved surface which would show by its undu- 

 lations the state of the aerial movements, and might be contoured. Unfortu- 

 nately, the changes of direction are so abrupt and large, that it is absolutely 

 impossible to exhibit in this way the conditions of any short period ; but it is 

 probable that it may be different with the hourly or even annual mean of a 

 considerable number of years; and I venture to recommend it, or some equiva- 

 lent, as an object worth the attention of meteorological inquirers. 



T. E. Robinson. 



Armagh Observatoet, 

 Juw 8, 1850. 



