Food: Principles of Measuring - How to Measure Ingredients

The uniform accuracy of results obtained by professional cooks, bakers, and caterers is due, in great degree, to the fact that the measurement of ingredients called for by their recipes is accurately determined by weight, and the temperature of their ovens is definitely ascertained by means of the thermometer. Thus the conditions surrounding the food cooked are made identical, and uniformity in the product necessarily follows. Any cook can obtain similar results by like means, and a good pair of scales in the kitchen may be regarded as one of the marks of a good housekeeper. There are numerous occasions when the use of scales is necessary, and there is no question but that measurement by weight could be advantageously made use of far oftener than is usually done at present.
As long as the housewife is content to measure rather than to weigh she will have to expect her products to be lacking in uniformity for no two people measure exactly alike and probably no one person measures twice in the same way. But if measurements are to be persistently used, it is necessary that the housewife shall take as many precautions as possible toward attaining a reasonable degree of accuracy in her work.
All dry ingredients, such as flour, meal, confectioner's and powdered sugar, should be sifted before measuring. Mustard, baking powder, cream of tartar, soda, salt, and spices should be stirred to lighten and free them from lumps. To dip a measuring cup into flour or other dry material in order to fill it and then to shake the cup to level its contents, condenses or packs the flour and causes the cup to contain more than the recipe calls for. The material should be added tablespoonful by tablespoonful, taking care not to shake the cup until the cup is well filled. The contents should then be leveled by means of a case knife.

All ingredients, measured by the tablespoonful or teaspoonful, are measured level unless otherwise stated. To measure a spoonful, fill the spoon and level it with the back of a case knife. For a half spoonful, first measure a spoonful, then divide it in halves, lengthwise, with a thin knife blade. To measure a quarter spoonful, first measure a half spoonful and divide it crosswise, a little nearer the back than the point of the spoon, to allow for its curvature. This is equivalent to one saltspoonful. Butter, lard, and other solid fats are measured by packing them solidly into the spoon or cup and leveling with a knife. Butter should be measured before melting, unless melted butter is stated in the recipe, in which case it should be measured after melting.
A cup which holds half a pint, is the common standard of domestic measure. This cup has straight sides divided into fourths and thirds. It may be obtained at any good 5- and 10-cent store or mailorder establishment.
The following are tables of measurements, all measurements being level.

(page 49 in the book)