The novice had better postpone the operation till the fourth day, when he, too, will have no trouble in detecting the germ. The same rule will hold good with all white eggs, but dark-brown eggs should not be tested till the sixth or seventh day. This can be done much sooner, but a large machine full cannot be tested in a minute, and the eggs should be far enough advanced so that the operator can take two or three in his hand at once, and passing them before the flame, readily detect the germ. I never use a tester for duck eggs, as a simple flame is sufficient, the egg being translucent. During the first stages of incubation the germ is very distinct, even at the third day. The clear eggs are reserved for family use or disposed of to bakers. An expert cannot distinguish them from a fresh-laid egg, either in taste or appearance. There is usually a small percentage of the eggs that are slightly fertilized, in which the germ will die during the second or third day. These can be readily detected at the end of the fifth day, and should be taken from the machine, and reserved as food for the young ducklings. Another and potent reason why all infertile eggs, and those with dead chicks in them, should be taken out of the machine, is that after the circulation begins in the egg, especially during the last part of the hatch, the temperature of a live egg is several degrees higher than that of a dead one. The one radiates heat, the other absorbs it; so that if the operator is running his machine 102 degrees, with his glass on a dead egg, he may be all unconsciously running it at 104 or 105 degrees on a live one. I had a letter from a man some time ago stating that his thermometers were developing strange freaks,--that though they registered the same while in water, at 103 degrees, when lying on the eggs a few inches from each other in the machine, they were several degrees apart, and wishing to know by which he should run, the higher or lower. I wrote him that his glasses were all right, and that he was the one at fault, and had he followed instructions and tested his eggs he would have had no such trouble. He wrote that as his machine was not quite full, and as he had plenty of room, he neglected to test them, thinking it would make no difference.