15. A "hazard" shall be any bunker of whatever nature--water, sand, loose earth, mole-hills, paths, roads or railways, whins, bushes, rushes, rabbit scrapes, fences, ditches, or anything which is not the ordinary green of the course, except sand blown on to the grass by wind, or sprinkled on grass for the preservation of the links, or snow or ice, or bare patches on the course. 16. A player or a player's caddie shall not press down or remove any irregularities of surface near the ball, except at the teeing-ground, under the penalty of the loss of the hole. 17. If any vessel, wheel-barrow, tool, roller, grass-cutter, box, or other similar obstruction has been placed upon the course, such obstruction may be removed. A ball lying on or touching such obstruction, or on clothes, or nets, or on ground under repair or temporarily covered up or opened, may be lifted and dropped at the nearest point of the course, but a ball lifted in a hazard shall be dropped in the hazard. A ball lying in a golf hole or flag hole may be lifted and dropped not more than a club-length behind such hole. 18. When a ball is completely covered with fog, bent, whins, etc., only so much thereof shall be set aside as that the player shall have a view of his ball before he plays, whether in a line with the hole or otherwise. 19. When a ball is to be dropped, the player shall drop it. He shall front the hole, stand erect behind the hazard, keep the spot from which the ball was lifted (or, in the case of running water, the spot at which it entered) in a line between him and the hole, and drop the ball behind him from his head, standing as far behind the hazard as he may please. 20. When the balls in play lie within six inches of each other, measured from their nearest points, the ball nearer the hole shall be lifted until the other is played, and shall then be replaced as nearly as possible in its original position. Should the ball farther from the hole be accidentally moved in so doing, it shall be replaced. Should the lie of the lifted ball be altered by the opponent in playing, it may be placed in a lie near to, and as nearly as possible similar to that from which it was lifted. 21. If the ball lie or be lost in water, the player may drop a ball, under the penalty of one stroke. 22. Whatever happens by accident to a ball _in motion_, such as its being deflected or stopped by any agency outside the match, or by the fore-caddie, is a "rub of the green," and the ball shall be played from where it lies. Should a ball lodge in anything moving, such ball, or, if it cannot be recovered, another ball, shall be dropped as nearly as possible at the spot where the object was when the ball lodged in it. But if a ball _at rest_ be displaced by any agency outside the match, the player shall drop it or another ball as nearly as possible at the spot where it lay. On the putting-green the ball may be replaced by hand.