In filling orders for eggs at a distance I make it a point never to send eggs more than four days old, or with less than seventy-five per cent of fertility. Transportation, even over rough roads, does not affect their hatching, except in extreme warm weather, when the contents, becoming thin and slightly evaporated through the heat, are apt to mix, when they will surely cloud and rot. I have often sent eggs 2,000 miles, with the report that every egg produced a duckling. With machine ready and running steadily the eggs may be introduced at once. They need no moisture now, and it is not necessary to disturb them for the first forty-eight hours. How to Choose and Use Thermometers. Place your thermometer on the eggs in middle of egg-tray. Be sure, in the first place, that you get a good glass, as all depends upon its accuracy. Do not use one with the mercury bulb lying upon a solid metal plate, as the refraction of heat upon the plate from the tank above will always run that glass one or two degrees higher than the heat in the egg-chamber, but get one, if possible, with a hole in the plate opposite the bulb, so that the heat can play around the bulb and through the plate, giving the correct heat of eggs and chamber. Do not hang your glass up over the eggs, or put it down between the eggs, but lay it on them, for the reason that, though either of these positions may be all right during the first twelve days of the hatch (if your eggs are fertile), they will surely be all wrong during the last part. I will endeavor to explain this thing, so that the novice will understand how important it is. Before circulation begins in the embryo chick or duck, and there is no animal heat in the egg, the temperature of the egg chamber regulates that of the eggs. But after circulation begins, and especially during the latter part of the hatch, when the rapidly-developing young bird throws out a great deal of heat, the thing is often completely reversed. For instance, a glass may be hung one inch above the eggs and another placed immediately on the eggs beneath. The one above may register 102 degrees; the one below, on the eggs, will register 105 degrees,--conclusively showing that the eggs are now, by their own caloric, heating the egg-chamber.