Page:Science vol. 5.djvu/88

 �I Vol- v., MoTit

��to Ihm of Aphides. It is dark, not light, in color; disagreeable, not pleasant, to the taste; distssteful to the bees, and not coveted by them; iinwholesorae for winter food for bee', and pOBitively injurioiiB l-o honey which is to be placed ou the market.

Yet this bark-louse cloud has ils silver lining. In early spring, before the flowers bloom.lt atimiilatea the bees to their highest eudeavor In breeding, so that well-stocked colonies greet the clover-bloom. The apiarist has only to extract this dark, Ill^flavored honey at the dawn of the elovcr season, to convert a seeming ill into an unmixed blessing ; especially as Ibis coccld nectar is equally as good m honey for vari- ous manufacturing purposes, as the making of print- ers' rolls, the flavoring of cigars, and the mannfacture of lioney-cakes. Knowledge and caution on the part of the bee-keeper will keep this dark honey wholly separate from the other, and thus eliminate all harm, iind make the former of no small advantage to him. A. .1. Cook.

��ECONOMY OF FUEL.

How much can be accomplished in the way of economizing in fuel Is shown by the results obtained lately on a trip of the Burgos, a freight-steamer built to carry cargo cheaply at a slow speed. Her engines are on the triple compound system, where the steam — in this case from a boiler-pressure of a hundred and sixty pounds per square inch — is expanded in three cylinders in succession. The average speed at sea, in all weathers, is very nearly ten miles per hour. In a voyage from Plymouth, Eng-. to Alexandria, on the way to China, with a cargo weighing 5,6UO,00 ponndt, and in a distance of 3,380 miles, the con- sumption of coal was 136 tons (or 282,240 pounds), being at the rate of 83.5 pounds per mile, or .03 of a pound per ton of cargo per mile; in other words, half an ounce of coal propelled one ton of cargo one mile. The RailFoad gazette very neatly saja, " Asaiiming that paper is as eOlclent a fuel as coat, we have only to burn a letter ou board this steamer to generate and utilUe enough energy to transport oue ton of freight one mile. It is difScult to realiie that so trifling an act as burning a letter involves such a waste of useful euergy, or can have any reference to the energy suffi- cient to pei-forni a feat which, under less favorable requires a couple of horses and a
 * r for about half an hour,"

We may eontraat with her |«rfonuance that of the steamship Oregon, of the Gulon line, where every thing is sacrificed to speed. The Oregon has engines of 13,000-horse power, 12 boilers, 72 furnaces, a cargo capacity some seven or eight limes that of the Bui^ott, but Intended for passenger business largely, attains an average speed of l7.9fcnots (or 20.6 miles) per hour, and bums 337 tons of coal per hour, combustion taking place at the rate of over lli tons of coal for eacli mile traversed. The cost of her coal for the voyage is put at considerably over $16,000.

The best locomotive performance in this country of which there is authentic record gives a consumption

���of about two ounces of coal per ton uf freight hauled one mile, at the rate of thirteen miles per hour includiug stoppages, and rising to Ave or roa per ton per mile on grades of from fifty to seventy '

��EXPLOSIVES AND ARMOR-PLATE.

During the last session of congress the theory was advanced that the effect of a moderate weight of dynamite, exploded in contact with the plates of a modern armor-clad ship, would be disastrous to the vessel. The Naval bureau of ordnance has lasted this by exploding charges of gun-cotton and dyna- mite varying in weight from five to oue hundred pounds, against a vertical target composed of nine layers of one-inch wrought- iron plates, strongly backed with twenty inches of wood, and braced so as to represent, aa well as possible, the stiffness of the KJdes of a ship. Though much more work was dune than it is likely would ever be performed against the armored aide of a ship, the target was not materially injured.

In the course of tbeseexperlraentsit was apparently shown that the point at which a charge of n blgll explosive is Ignited has an importaut effect upOD the work done, since the effects of these charges were readily increased ur diminished very materially, according as they were ignited on the side away from or adjacent to the plate; and this, too, notwithstanding the distance between the points of ignition in the two cases was only a foot. It is claimed that this re- sult shows that the charge of a. high explosive cannot furnish any tamping effect, but that to produce the greatest effect the ignition mutt be at some Interior point of the explosive, well toward the rear. It also appears that the effects do not increase proportion- ally to the increase of the charge when the igulti'in surface remains constant.

The gradual ignition nf the charge, even In the case of so violent an explosive as gun-cotton, was strikingly illustrated by the fact that when twenty-«lx pounds of wet compressed disks of that material were piled upon an iron plate, and exploded from the tO]i (without tamping or cover), accurate impressions of the lower disks in the pile were stamped upon the Iron underneath them. In this case there did nut seem to be the least doubt concerning the complete explosion of the charge,

Experiments were also successfully made in firing shells charged with gun-cotton from ordinary rifled cannon, twelve rounds being fired from the twelve- pound howilMf, and thirteen rounds from the eighty- pound breech-loading rifle, and the ordinary ser- vice charges of gunpowder being used In the gun. Three uufuzed shells, charged with gun-cotton, were fired tram the elghty-po under against the target used in the dynamite experiments. The shells exploded with great violence, on impact; but the damage to the target was very slight, as the explosion took place before any practical penetration was effected. In view of recent successful experiments with a fuie

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