THE TEADE WIND. I33 



the open ocean. Between the Canaries and Cape Verde, during the 

 Northern summer months, it blows from N.N.E. and N.E. for 55 days out 

 of every 100 days. 



During the winter months, from January to March, the wind in the 

 neighbourhood of Cape Verde draws very much toward the land, or from 

 N.W. and West. This point will be more fully discussed in a later part of 

 this work. 



(57.) In order more fully to exemplify the duration and direction of the 

 Trade Wind, the adjoining diagrams have been selected from the Chart of 

 the North Atlantic Ocean. They will show the particulars of the wind 

 between the parallels of 10° and 20° N. ; that is, in the main strength of 

 the N.E. Trades. They have been adapted from Maury's Pilot Charts, as 

 appeared before (48), and will show the per centage of winds from any 

 quarter in each of the foui- calendar seasons ; and also the amount per cent, 

 of Calms encountered. The plate will explain the different arrows (indi- 

 cating the seasons) which are supposed to represent winds blowing toward 

 the centre of the circle, because the winds take their names from the 

 quarters from whence they come, the North point being supposed to be at 

 the top of the page, the South at the bottom, the East to the right, and the 

 West to the left hand. The length of the uppermost arrows is propor- 

 tioned to the duration or frequency of that wind, according to the scale 

 attached ; so that by applying the compasses to any one of the arrows, it 

 will give, according to the scale, the amount of wind per cent, for that 

 direction. These arrows are given for sixteen points of the compass, omit- 

 ting the " by " points, in each season. The arrows altogether make up 

 the length of 3 inches, that of the scale given.* In the centre of each 

 diagram is given the amount per cent, of Calms encountered in the respective 

 seasons. As the Force of the winds is not given in the Pilot Charts, this 

 register of the Calms is the more important, as it is the only scale we can 

 apply to the force of this wind ; as, by analogy, we may argue that where 

 Calms predominate, there also do light and baflfling winds, and the reverse. 



(58.) An analysis of the wind-roses in Captain Maury's Chart, from which 

 these diagrams are constructed, will give the following figures as to the 

 prevalence and direction of the winds along the main strength of the N.E. 



• There is one remark which it is necessary to make here respecting these wind obser- 

 vations (220,000 in number). They have been taken from a vast quantity of different 

 log-books, whose remarks are not made with the definite accuracy necessary for scientifio 

 precision. A slight inspection of the figures given on the diagram, or of the Board of 

 Trade charts, will show that in these data the direction of the wind is loosely and in- 

 definitely given throughout. Thus, a wind between North and East is set down as a 

 N.E. wind, &c., &c., and not so often as N.N.E. or E.N.E. as must reaUy occur. Con- 

 sequently, the arrows representing these principal or cardinal points are longer than 

 they ought to be, and the intermediate ones shorter ; in fact, they form a zig-zag or 

 irregular curve around the centre ; whereas it is manifest that this curve should be some- 

 what symmetrical, and that the wind blows from the intermediate points in some regular 

 ratio to those on either side of it. Until we get more exact records added together in 

 great numbers, as has been done in the PUot Charts with these imperfect logs, it is 

 plainly futile to draw any precise or refined conclusions from their teaching. This is 

 not said to underrate their value. To the sailor, who only requires a general exact 

 knowledge of the subject, they teach as much almost as he requires to know as to the 

 direction of the wind. 



