It should be noted that the computations can almost always be done mentally, as analyses of different food stuffs of the same kind vary considerably, so that to attempt very accurate calculations with two or three decimal places would be straining at a gnat after swallowing a camel. Excepting bread stuffs and other cereals, which have both a high percentage of one nutrient and are used in considerable quantities, it is rarely that the day's ration of any one of food stuffs exceeds the capacity of one line of the scale bar. Indeed, on the Chittenden diet, the entire protein ration would not exceed this capacity, nor should the total fat go much beyond the limit of the scale bar. Excepting for bread stuffs and sugar when used freely, no one food stuff is likely to exceed the limit for representing carbodydrates. When, however, two or more lines are required, it simplifies the addition to stop at 50 on the bar. It will be noted that the vertical lines of the P and F and the convexity of the terminations of the C furnish convenient measuring points. While it is scarcely necessary to regard fractions, the carriage may be held by hand at an intermediate point between the divisions. As for all scientific work, a visible writing machine is preferable in many ways, but any ordinary typewriter can be used.

Measuring with the dividers, which will stretch to indicate the fat and the protein ration and which will require not over four or five measurements for even a large carbodydrate ration, we find, in the present instance, the protein measurement to be 11 inches (110 grams), the fat 6.9 (69 grams), the carbohydrate 27.1 plus (271 grams).

Graphic Method Of Calculating Calories On The Principle Of Proportionate Triangles

Since one gram of fat, protein and carbohydrate, respectively, yields 9.3, 4.9 and 4.1 calories, triangles having a common angle and base line, with bases of 1, 4.1, 4.9 and 9.3 units will have proportionate lengths on corresponding parallel sides, so that, if this side is marked off in units for the smallest triangle and read as grams, corresponding sides of the larger triangles will measure, in corresponding units, calories yielded by the respective kinds of nutrients. It is not necessary that the triangles should be right angled, although this is the most convenient construction, nor that the units for the base line should be the same as for the parallel sides. Solely on account of the difficulty of measuring small distances, it is better to multiply the dimensions of the unit triangle by ten, so that the distances from the common angle will be 4.1 for carbohydrates, 4.9 for proteins, 9.3 for fats and 10 for the triangle used to measure grams. On account of this construction, each unit read as grams will correspond to ten units read as calories. Obviously, the larger the triangles, the more accurate the reading, and the larger quantities of organic foods can be estimated at one reading. On the other hand, it is inconvenient to deal with too large charts.

Half-inch or two-centimeter units are convenient for measuring the base line, and quarter-inch or centimeter units for each ten gram or 100 calories on the parallel sides will enable one to read off a moderate day's ration of any organic food constituent at once, and with a fair degree of accuracy, on a chart not too large for convenient handling.