From these experiments it appears that the electric arc, and still more the mercury vapour lamp, are likely to prove of great value to the market gardener. As compared with the arc lamp, the mercury vapour lamp has the great advantage of requiring scarcely any attention, and also it uses less current. Unlike the products of ordinary forcing by heat, the plants grown under the influence of the mercury vapour light are quite sturdy, so that they can be planted out with scarcely any “hardening off.” The crop yields too are larger, and of better quality. The wonderful effects produced by the Cooper-Hewitt lamp are certainly not due to heat, for this lamp emits few heat rays. The results may be due partly to longer hours worked by the plants, but this does not explain the greater accumulation of chlorophyll and stronger development of fibre. Most of us are familiar with the yarn about the poultry keeper who fitted all his nests with trap-doors, so that when a hen laid an egg, the trap-door opened under the weight and allowed the egg to fall through into a box lined with hay. The hen then looked round, and finding no egg, at once set to work to lay another. This in turn dropped, another egg was laid, and so on. It is slightly doubtful whether the modern hen could be swindled in this bare-faced manner, but it is certain that she can be deluded into working overtime. The scheme is absurdly simple. Electric lamps are fitted in the fowl-house, and at sunset the light is switched on. The unsuspecting hens, who are just thinking about retiring for the night, come to the conclusion that the day is not yet over, and so they continue to lay. This is not a yarn, but solid fact, and the increase in the egg yield obtained in this way by different poultry keepers ranges from 10 per cent. upwards. Indeed, one poultry expert claims to have obtained an increase of about 40 per cent.