502 PROFESSOR TATT ON 



sponding abscissa, in order to give the actual path when the speed of the head-wind 

 is about 17 miles an hour, and the initial speed about 275. (The exact values of this 

 and of the actual angle of projection must be calculated by means of the preceding 

 formulae : — but they are of little consequence in so rough an illustration as the present, 

 especially as (f> and U/V are both small.) The corresponding trajectory is shown in 

 fig.7. If we use the same relative path for wind of 25*5 miles per hour, the actual 

 initial speed must be about 262*5, and the true path is fig. 8. Finally, fig.9 gives the 

 result with actual initial speed 250, and head- wind blowing at 34 miles an hour. Here, 

 again, a kink is produced in the actual path, but it is due to a completely different 

 cause from that of fig. 4. And it is specially to be noted how much the vertex is 

 displaced towards (and even beyond) the end of the range. 



21. It is not necessary to figure the result of a following wind, for such a cause merely 

 lengthens the abscissa? in a steadily increasing ratio, and makes the carry considerably 

 longer, while placing the vertex more nearly midway along the path. But it is well to 

 call attention to a singularly erroneous notion, very prevalent among golfers, viz., that 

 a following wind carries the ball onwards ! Such an idea is, of course, altogether 

 absurd, except in the extremely improbable case of wind moving faster than the actual 

 initial speed of the ball. The true way of regarding matters of this kind is to remember 

 that there is always resistance while there is relative motion of the ball and the air, and 

 that it is less as that relative motion is smaller ; so that it is reduced throughout the 

 path when there is a following wind. 



Another erroneous idea, somewhat akin to this, is that a ball rises considerably 

 higher when driven against the wind, and lower if with the wind, than it would if there 

 were no wind. The difference (whether it is in excess or in defect will depend on the 

 circumstances of projection, notably on the spin) is in general very small ; the often 

 large apparent rise or fall being due mainly to perspective, as the vertex of the path is 

 brought considerably nearer to, or further from, the player. 



These approximations to the effect of wind are, as a rule, very rough ; because in 

 the open field the speed of the wind usually increases in a notable manner up to a con- 

 siderable height above the ground, so that the part of the path which is most affected is 

 that near the vertex. But the general character of the effect can easily be judged from 

 the examples j ust given. 



When the wind blows directly across the path, the same process is to be applied. 

 It is easy to see that the trajectory is no longer a plane curve ; and also that, in every 

 case, the carry is increased. But, in general, " allowance is made for the wind," i.e. the 

 ball is struck in such a direction as to make an obtuse angle with that of the wind, more 

 obtuse as the wind is stronger. In this case the carry must invariably be shortened. 

 But without calculation we can go little beyond general statements like these, 



