This section is from the book "The Pure Food Cook Book: The Good Housekeeping Recipes, Just How To Buy, Just How To Cook", by Harvey W. Wiley. Also available from Amazon: The Pure Food Cookbook.

WHY is it I can never get an egg cooked to suit me in my own house ? " asks many a man.
Because, oftentimes, the egg is put into cold water, and the time is then noted, but even when the egg has been in the water the requested number of minutes, it has not been cooked at a sufficiently high temperature for a sufficiently long period. The difficulty is to obtain uniform results, many factors affect the result: the size and age of the egg, the size and kind of utensil and its position on the stove, the temperature of the egg (an egg from a refrigerator takes, of course, longer to react to heat) and the amount of water. The table-cooked egg is probably the surest, in obtaining uniformly cooked eggs.
Taking all these possible conditions into account, the best way to cook or " boil " an egg is not to boil, but to cook it below the boiling point, say at about 180 to 190 degrees, F., because the egg albumen is toughened and rendered leathery and indigestible when submitted to the boiling point of 212 degrees, but remains jelly-like, though firm, at the lower range of heat. Soft cooked eggs should be cooked below boiling point. Following is a test made in the laboratory of the University of Illinois:
" Using a granite-ware stewpan of one-quart capacity, one pint of water was heated over a gas flame; when the water boiled the gas was turned off, and an egg, which had been kept in a refrigerator, was dropped into the water. Without disturbing the vessel, it was covered closely and the egg allowed to remain in the water six minutes." It was then cooked soft. When the egg was dropped into the water the temperature fell immediately to 185 degrees Fahrenheit, and then slowly to 170 degrees. If the egg remained in the water eight minutes it was medium-cooked, the temperature of the water at the end of the period having fallen to 162 degrees.
Hard-" boiled " eggs should be cooked for forty-five to sixty minutes at 180 to 190 degrees, or they will be tough and not mealy. If cooked below boiling point they will be more easily digested. Should the shell crack, pierce several small holes with a pin to keep contents from flowing out.
Good results with soft cooked eggs can be obtained if attention is given to details, and if the cook will only remember the experience gained the last time she cooked an egg in the same way. It is a safe rule, if one does not have a thermometer, to keep the water below boiling point. A double boiler is a splendid device for just this process, as the water may boil below, while above it can be kept below the boiling point. It is best, however, not to let the water boil even in the lower saucepan.
In preparing for an egg dish of any sort, first break the egg by a swift stroke of a knife into a dish that is not to be used for the mixing. Then if by mischance the egg is not up to the mark, it can be discarded and will not spoil the rest of the mixture.
For poached eggs, have the water a little below 212 degrees, by pouring boiling water from a saucepan into the shallow pan, which has been brushed over with oil or butter. Break the egg carefully into a cup and slip gently into the water, thinking all the time of having it float, so lightly must it be transferred. The egg quickly reduces the temperature to 185 degrees, which is correct for poaching an egg. The top of the yolk should be kept slightly emerging from the water. Let the egg cook gently. Spread some water over the egg with a spoon and when a film has formed over the yolk and when the white is firm, lift each out with a skimmer, drain, smooth the edges with a knife, if necessary, and place on hot toast, which has been prepared beforehand. If the eggs are fresh and cooked correctly, they will not need trimming. Put a piece of butter, some pepper and salt on the egg, and serve hot on very hot plates.
When properly poached the egg is jelly-like throughout and the yolk is covered with a white film. Egg poachers and muffin rings are often used for poaching eggs. Salt and vinegar are oftentimes put into the water to prevent the soluble albumen from being dissolved. This also adds flavor to the eggs. Half a teaspoonful of vinegar for six eggs will be sufficient. Poaching eggs is no easy matter. Even a hotel chef will admit this; but a little care will bring good results.
The varieties of poached and boiled eggs reach the hundreds. The eggs are cooked with cream, sauces, anchovies, and combined with truffles, mushrooms, cheese, sausages, etc., etc. The following recipes are variations of the " boiled " and poached egg:
 
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