The novice should also bear this in mind and religiously observe it: Avoid any upward or backward motion of the rod at the instant when the fly falls upon the water or immediately thereafter. In line with this it may also be said that no matter how fast the current may be, the angler should never begin to strip in the line until the fly is well started on its downstream journey. The seasoned wet fly-fisherman, upon his initial attempts at casting the dry fly, will doubtless find that he has an habitual tendency to raise the point of the rod at the moment when the forward cast has been completed and the fly has just fallen upon the surface of the stream; if this is done, the fly is at once pulled under the surface--drowned--and the habit is one which must be constantly resisted.
The same may be said of the tendency to begin stripping in the line prematurely while it is still taut; the slightest pull upon the line at this time is at once communicated to the fly and either drags or drowns it. The proper and strictly necessary procedure, then, for the dry fly-caster is this: At the completion of the forward cast hold the rod absolutely motionless for a moment until the fly, floating down, has created more or less slack line, in accordance with the character of the water over which the cast has been made; then slowly bring up the tip of the rod or carefully strip in the line, or both, bearing in mind that to float the fly successfully there must always be more or less slack line between rod-point and fly.
As above noted, the best way to prevent drag is to first study the nature of the water over which the cast is to be made, eventually casting from the stand which seems most favorable for the cast's coming off well. If, however, it is absolutely necessary to cast so that the fly will fall upon a slower current than will the line or upon a swifter run than will affect the line, the only remedy is to cast a slack line--the fly will then float for a greater or less distance without restraint. If the fly is cast upon a still or slow place while the line rests upon swift water, drag will not set up until the slack line has passed downstream and begins to pull upon the fly. In the opposite instance, when the fly is on a swift run and the line in slow water, the cast being so made that the slack lies in the swifter current, the fly will float without drag until it has taken up the slack, when the line will retard it. How, when, and where drag will occur is not only a matter of the set and strength of the currents acting upon fly and line, but also dependent upon the point from which the angler casts in relation to the currents--obviously a matter which cannot be detailed in a manner to cover satisfactorily even a few of the situations where drag is likely to occur. The angler must practically solve each problem of this sort for himself, as it is presented in the course of the day's fishing. But in practically every case the slack-line cast, varied to suit the occasion, is the best way out of the difficulty.