ment.

that it is found necessary to increase the diet for longer periods to 6362 grains of carbon and 317 of nitrogen. Of course, military prisoners require more food than convicts, independently of the nature of the work at which they may be employed, inasmuch as they are larger men, and the ordinary physiological wants of the body demand a proportionately greater amount of nutriBut the difference in stature between the two classes of prisoners does not account for such a difference in diets, and I have no doubt that convicts employed at active out-door labour would require at least as much as is represented by the average diet for ordinary labour given by Dr. Letheby-viz. a diet containing 5688 grains of carbon and 307 grains of nitrogen daily, to maintain them in good health, and prevent serious loss of weight.

SECTION IV.-CONSTRUCTION OF DIETARIES.

By reference to the numerous data already given, it will not only be easy to calculate the nutritive value of any given dietary, but a reliable opinion may be formed as to its suitability as well as sufficiency under specified circumstances. It now remains to point out the more important principles which ought always to be kept in view in the construction of dietaries; and, apart from the influence of work, which has already been considered, they may be briefly summarised as follows:

1. Influence of Sex.In the case of in-door operatives, the dietaries of women should be about one-tenth less than those of men.

2. Influence of Age. Up to nine years of age, a child should be dieted chiefly on milk and farinaceous substances. At ten years of age it will require half as

much nutriment as a woman; and at fourteen quite as much as a woman. Young men who have not reached their full growth, but who are doing the same amount of work as adult men, require more food than the latter. 3. Selection of Food.-This embraces a variety of considerations, such as

(1.) The relative proportions of proximate constituents. These have already been shown in Moleschott's numbers quoted by Dr. Parkes, and they correspond very closely with those given by Dr. Letheby-viz. 22 of nitrogenous substances, 9 of fat, and 69 of starch and sugar. Whether the diet be mixed or purely vegetable the same proportions hold good, and the results of experience prove that they are substantially correct. For example, articles of food which are deficient in one class of constituents, are invariably associated with others which contain an excess of them. Thus we have butter, or milk, or cheese, with bread; bacon, with veal, liver, and fowl; melted butter or oil, with fish; and so on. Such combinations are also of great service in aiding the digestibility of food. For reasons to be afterwards stated, every dietary should contain fresh vegetables.

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(2.) Variety of Food.-But even when the proper proportions of constituents are provided for in a dietary, it is further necessary that certain articles belonging to the same class be varied from day to day, otherwise the appetite cloys. Beef should alternate with mutton, for example; or variety may be secured by different modes of cooking the same article. Indeed, it is not too much to say that the art of cookery is a matter of national importance, not only because it renders food palatable, but because the more it is studied and practised the greater is the economy which may be effected. It is

chiefly in this respect that beverages, condiments, etc., become such valuable dietetic adjuncts.

(3.) Digestibility.-This also in great measure depends upon the mode of cooking.

(4.) Price. For much practical information on this and other points, see Dr. Edward Smith's Practical Dietary, or his Report on the Food of the Lancashire Operatives, in the Fifth Report of the Medical Officer to the Privy Council.

4. Number and distribution of Meals. Experience teaches that three meals daily are best suited to the wants of the body, Dr. Edward Smith, in his physiological diet of 4300 grains of carbon and 200 of nitrogen, distributes the amounts as follows:

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5. Climate. Other things being equal, carbonaceous substances ought to contain a preponderance of fatty constituents in cold climates, and of starchy or farinaceous, in warm climates. This also applies to seasonal

variations.

SECTION V.-PRESERVED FOODS.

Only a few of these need be mentioned.

1. Liebig's Extract. This is more especially valuable to the traveller or the invalid. According to Dr. Parkes it is very restorative, removing all sense of fatigue after great exertion. Its nutritive qualities are inferior to those of ordinary beef-tea, but it can often be

taken by an invalid when beef-tea would be rejected; and it has the further advantage of being readily prepared.

2. Preserved Meat.-What is known as Australian meat has the most extensive sale. Weight for weight, it is not so nutritious as properly cooked fresh meat, because the process of preservation requires that it should be over-cooked. The great difference in price, however, more than compensates for this slight disadvantage, and on the score of economy alone it deserves to be extensively used. Large quantities of it are now consumed in workhouses and asylums. It is best used cold, or warmed and mixed with potatoes and vegetables to form a stew; or it may be minced and warmed. Dr. Williams' experiments in the Sussex County Asylum, the patients were allowed amounts equal to the uncooked fresh meat daily ration, with the result of a slight gain in weight in 13 of the 20 experimented on at the end of a month, the weight of the others remaining stationary.

In

3. Preserved Vegetables. When fresh vegetables cannot be procured in sufficient quantity, dried vegetables should be employed to make up the deficiency. In lieu of potatoes in the early part of summer, preserved potatoes may be used, but as they are apt to pall on the appetite, other substitutes, such as a mess of rice and cabbage, or pease-pudding, should be given on alternate days.

4. Preserved Milk. According to recent analyses conducted by Mr. Wanklyn, the condensed milk prepared by the Anglo-Swiss, Newnham's, and the English Condensed Milk, Companies, consists of pure milk sweetened with a little sugar. As one volume of the

condensed milk contains the nutritive material of four

volumes of fresh milk, it should be diluted with three times its volume of water when used.

SECTION VI.-EXAMINATION OF FOOD.

It need scarcely be said at the outset that a thorough practical knowledge of the qualities and appearances presented by the various articles of diet, in their wholesome or unadulterated state, is a necessary qualification for the detection of unwholesome or adulterated speci

mens.

1. Meat. The characters of good meat may be enumerated as follows:

(1.) On section, it should present a marbled appearance from intermixture of streaks of fat with muscle. This shows that the animal has been well fed.

(2.) The colour of the muscle should neither be too pale nor too dark. If pale and moist, it indicates that the animal was young or diseased; and if dark or livid, it shows that in all probability the animal was not slaughtered, but died with the blood in it.

(3.) Both muscle and fat should be firm to the touch, not moist or sodden, and the latter should be free from hæmorrhagic points.

(4.) Any juice exuding from the meat should be small in quantity, be of a reddish tint, and give a distinctly acid reaction to test-paper. Good meat should dry on the surface after standing a day or two. The juice of bad meat is alkaline or neutral.

(5.) The muscular fasciculi should not be large and coarse, nor should there be any mucilaginous or purulent-looking fluid to be detected in the intermuscular cellular tissue.

(6.) The odour should be slight, and not by any