Digestion of Foods by Swine.

Experiments are reported by Wolff, Wildt, and Heiden, who with assistants have tested the digestion of quite a list of materials, such as barley, maize, pea-meal, cocoa-nut cake, potatoes, roots, milk, flesh-meal, fish-guano, and in one case cockchafers. Sour milk is not wholly digested by swine; but it seems to increase the digestion of other foods, as grain, fed with it. Cocoa-nut cake proved a palatable and useful food for swine. The same is true of cockchafers, dried and ground. The digestibility of flesh-meal made of the residue left from the preparation of Liebig's meat-extract in South America has been tested quite extensively. Wolff found, as the average of seven experiments, 96.6 per cent. of the albuminoids. and 87.3 per cent. of the fat of the flesh-meal to be digested by pigs.

Digestion of Foods by Sheep.

Experiments on the digestive and nutritive values of various materials fed to sheep are reported by Wolff and Kellner, Weiske and Wildt. The most interesting results are those obtained with the use of animal foods, blood-meal, fleshmeal, and fish-guano. The general object of these experiments has been to test the digestibility and nutritive value of these foods, and the question whether they can be used to advantage to supply nitrogenous material in fodder for herbivorous animals. There is no reason, in the nature of the case, why they should not; and the several accurate trials that have thus far been made coincide with former experience in showing that the flesh-meal made of the residue left from the preparation of Liebig's meat-extract, dried blood, and fish-guano, are very easily digested; that though sometimes not very palatable at first, yet the animals soon get to like them, and that they form a very valuable food. In feeding fish-guano to sheep Kellner found 90 per cent. of the nitrogenous substances, 76 per cent. of the fat, and 15 per cent. of the mineral matters digested. Wildt found that sheep digested 95 per cent. of the albuminoids, and 98 per cent. of the fat of flesh-meal.

Value of Animal Waste as Food for Stock.-Fish-Scrap. From what has been said, it is clear that fish-scrap, meatscrap, dried blood, and the like are certainly valuable foods for sheep and swine, and probably for neat cattle. What makes them especially so is that, aside from their concentration and their easy digestibility, they consist mainly of nitrogenous matters and fats, the most precious ingredients and the ones most apt to be lacking in our common fodder materials. They will be used most profitably when mixed with foods poor in the albuminoids which it furnishes. Such are poor hay, straw, corn - stalks, corn, potatoes, and roots. The latter can thus be made into the best kind of food, and the fish-scrap at the same time be improved as a fertilizer. One great difficulty in the way of feeding fishscrap, dried blood, and meat-scrap has been their bad odor and taste, particularly after decomposition has set in. Of late, however, methods have been devised for preparing these materials in forms more palatable and less prone to decay. Meat-scrap is now offered in the market as light in color, nearly as fine and free from odor and tendency to decay, and fully as wholesome in appearance, as corn-meal. Two new processes for extracting oil from fish-Goodale's and Adamson's-are just coming into use, and give promise of furnishing a fish-scrap which can easily be made into an excellent food for stock. One great advantage of the fish meals made by these latter processes is that they have all, or nearly all, the flesh of the fish, and comparatively little else. Samples of both kinds, lately analyzed, have yielded over ten per cent. of nitrogen. A fish-guano made by Goodale's process gave some ten and one-fourth per cent. of nitrogen, and a little over seven per cent. of phosphoric acid. The fish-guano which has proved so valuable for food in European experiments was made of the heads and backs of codfish, and contained a much larger amount of phosphoric acid. Our products must be much better, because they have less phosphoric acid-that is to say, less bone-whose presence is objectionable.

We have seen what a loss comes to our agriculture from the exportation of meat-blood and fish products, as well as from the improper use as fertilizers of those which we keep

at home. In view of their worth as food for stock, the loss is still greater. As long as these wastes continue, farming must suffer. Rational economizing of such resources these will be among the best means for its recuperation.

Practical Inferences from Feeding Experiments.

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In general, the result of the year's work confirms the principle stated in previous summaries of the Annual Record, but too little understood by farmers in this country, that economy in feeding requires that the ration shall contain digestible albuminoids and carbohydrates in the proportions adapted to the specific wants of the animal and the purpose for which it is fed.

Comparing the results of late European experimenting with the ordinary practice of feeding in this country, it is manifest that we waste a great deal of food-material, and that this waste is due, more than to anything else, to the wrong proportions of ingredients in the fodder we use. From wrong choice of crops for raising (as, for instance, growing too little of nitrogenous crops, like clover, lucern, beans, and pease), from inadequate manuring of those we do raise, and from letting forage crops stand too long before cutting, our fodder materials lack nitrogen. We have concentrated foods, such as linseed and cotton-seed cake and meal, meat-scrap, and fish, which might supply this lack. But our farmers do not understand their value, and they are shipped by the hundreds of tons to Europe, where they are appreciated and properly fed. This is only one of many illustrations of the necessity of science for the best development of our agriculture. A most encouraging sign of the times is that farmers have come to feel this need, are calling for scientific investigation, and are applying its results in their practice.

ENGINEERING.

By WILLIAM H. WAHL, Ph.D.,

PHILADELPHIA, Pa.

RAILROADS.

From a record of the year's progress, as chronicled in the Railroad Gazette, we may affirm that in the field of railroad construction there has been reasonable activity, the increase in the mileage of the country having been about 3 per cent. The Gazette records 2111 miles as the actual record of new construction during 1877, or about 10 per cent. less than the figures of the preceding year. Most of the new roads, it is further noticed, were short, and of purely local importance.

In railroad legislation, the most memorable event of the past year was the decision of the Supreme Court of the United States in the so-called "Granger" cases, in which the principle was affirmed that state legislatures possessed the right to regulate and limit the rates charged by railroad companies where they have not parted with that right by charters. Another legal decision of importance, detailed by the Gazette, is that permitting the elevated-railway companies of New York City to proceed with the construction of their roads through the streets of that city without further hinderance. That the companies have not been slow to avail themselves of the privileges accorded them appears to be evinced from the vigor with which they are forwarding their plans; the probabilities being that the several rapid-transit roads will be practically completed and in operation before another year has passed, thus deciding the debated question of the practicability of elevated (as contrasted with underground) railroads for the requirements of large cities.

The Gazette closes an elaborate statement of railroad history with the following comments: The year closed much more cheerfully than it opened. . . . The prospect for the

new year is favorable. . . . The whole country is apparently convinced that it will have to accept low prices and small profits, and is satisfied to accept these conditions. No sudden return of great prosperity can be looked for, but a gradual return to better times is now held to be a sufficient cause for cheerfulness."

THE CANAL ACROSS THE AMERICAN ISTHMUS.

The constant agitation of this problem by the friends of rapid maritime transit will doubtless some day bear its legitimate fruit in the actual undertaking of a canal across one of the many routes surveyed by American and other engineers, although but little progress towards its solution has lately been made. The subject appears lately to have been attracting a considerable share of attention in France, the interest being at present centred upon the Darien route. De Lesseps, whose name figures prominently in the present discussion of this important project, advocates a line ascending the Tuyra or Darien River from the Pacific side as far as the island of Piriaque, from which point a straight cutting, 16,200 meters long, will connect the Tuyra with the Chucunaque near the point where the Tupisa flows into this latter river. The line proposed would then ascend the Chucunaque for 11,400 meters; then, turning to the northeast, would continue up the valley of the Tiati to a point where its projector, for reasons of economy, proposes to construct a tunnel rather than continue a deep cutting. This tunnel would pass to the south of the Peak of Ganol, under the remarkable ridge from which, on the one side, the Taquesa, the Tupisa, and the Tiati flow down towards the Pacific, and, on the other, the Tolo and the Acanti to the Atlantic. On emerging, the canal would continue through an open cutting about ten kilometers long down the valleys of the Acanti and Tolo to the deep waters of Port Candi. The probable length of the tunnel is estimated at between thirteen and fourteen kilometers, and the cost of making the whole canal at 600,000,000 francs (about $120,000,000). A surveying party, under the command of Lieutenant Wyse, of the French navy, is at present on the ground, working out the feasibility of the proposed route.

Having solicited of Mr. John C. Trautwine, a gentleman