Wind vanes in the trenches were of the simplest types and a great deal of ingenuity was displayed in fitting up weathercocks that would be capable of turning in really low wind--say, one with a speed of only two miles an hour. The bearings for the central rod were the greatest difficulty, but it was found that by boring out a rifle bullet a sharp pointed stick or a thick piece of wire could be got to revolve in the hollow bullet quite easily, what remained of the lead core acting as a kind of lubrication. The greatest nuisance of these wind vanes at first was that they were made so generally obtrusive that they could be seen from the enemy’s lines, and they nearly always drew fire from snipers, and sometimes actually from the artillery. Presumably the enemy thought that where the wind vanes were installed company headquarters were probably situated. The position of the wind vanes consequently had to be chosen so that the direction and speed of the wind would be measured several feet above the ground without the apparatus being too obvious. One of the simplest types of vane adopted, and one which could hardly be seen from any distance, was a bit of a stick to the end of which was tied ten to twelve inches of thin thread with a tiny bit of cotton wool at the end. When the wind is blowing the direction taken by the thread shows the line of the wind fairly exactly, and the behaviour of the cotton wool in rising and falling indicates the strength of the wind. The latter, however, was supposed to be measured by reference to Beaufort’s scale, which depends on the movement in wind of natural objects. Beaufort’s scale, which was devised long ago by an English admiral of that name, is as follows: Smoke moves straight up, speed of wind is _nil_; smoke slants, speed is two miles an hour; the wind is felt on the face, speed is five miles; paper, etc., move about, speed is ten miles; bushes are seen to sway, speed is fifteen miles; tree tops sway and wavelets are formed on water, speed is twenty miles; tree tops sway and whistle, speed is thirty miles. All of these arrangements for training and equipment of the troops were hurried on as quickly as possible, but at the same time sight was not lost of the probability of the German’s using gases different from the chlorine which had originally formed their stand-by. It was felt that a good all-round protection should be capable of keeping out not only chlorine and similar gases but also others which were quite likely to come into use.