of nutritive principles, (C), and one quarter of another class of nutritive principles, (N); 3rdly, that all the articles of common food admit of being placed, as below, in a Table, by which we see at a glance how much nutriment of class C, and how much of class N, is found in 100 parts, gross weight of any of them.  Thus, by a simple computation, the effective value of a dietary may be ascertained.  Class C, are the carboniferous principles, that maintain respiration; Class N, are the nitrogenous principles, that repair waste of tissue.  N will partly replace C, but at a great waste:  C will not replace N.

A large number of diets such as those of various armies and navies, of prisons and infirmaries, and of the ordinary diets of different classes of people, have been examined by aid of this Table, with surprisingly uniform results.  But these diets chiefly refer to temperate climates; it would therefore be a matter of great interest if travellers in distant lands would accurately observe and note down the weight of their own rations and those of the natives.  It is a great desideratum to know the lightest portable food suitable to different countries.  Any such reports, if carefully made and extending over a period of not less than two months, would be very acceptable to me.  To make them of any use, it is necessary that every article consumed should be noted down; and that the weight and state of health, at the beginning and at the end of the period, should be compared.

__________________________________________________
Table showing the quantity of Nutriment contained
in different articles of Diet.
____________________________________________________________

______
Articles of Diet    ..     C.                 N.
Total real
....................................................Nutri-
(Carboniferous.)  (Nitrogenous) ment per cent.
of gross weight.
____________________________________________________________

______
Wheat Flour............. 71.25 .......... 16.25 ....... 87.5
Bread................... 51.5  .......... 10.5  ....... 62.0
Oatmeal................. 65.75 .......... 16.25 ........82.0
Pearl Barley............ 67.0 ........... 15.0 ........ 82.0
Peas.................... 55.5 ........... 24.5 ........ 80.0
Potatoes (preserved
potatoes are thor-
oughly dry)........ .. 24.5 ........... 2.5 ..........27.0
Carrots................   8.5 ........... 1.5 ......... 10.0
Turnips.................. 5.7 ........... 0.3 .........  6.0
Cabbage.................. 6.7 ........... 0.3 .......... 7.0
Lean of Beef and Mutton . -   .......... 27.0 ......... 27.0
Fat of meat.............100.0 ..........  -   .......  100.0
Average Beef and Mutton  15.0 ...........20.25 ........ 35.25
Bacon....................62.5 ..........  8.36 ........ 70.86
Skimmed-milk Cheese ..... 0.4 .......... 64.6 ......... 65.0
White Fish .............   - ........... 21.0 ......... 21.0
New Milk ...............  8.0 ..........  4.5 ......... 12.5
Skimmed Milk ...........  8.0 ..........  4.5 ......... 10.0