74 



SCIENCE. 



[Vol. V., No. 103. 



to that of Aphides. It is dark, not light, in color; 

 disagreeable, not pleasant, to the taste; distasteful to 

 the bees, and not coveted by them; unwholesome for 

 winter food for bees, and positively injurious to honey 

 which is to be placed on the market. 



Yet this bark-louse cloud has its silver lining. In 

 early spring, before the flowers bloom, it stimulates 

 the bees to their highest endeavor 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 clover season, to convert a 

 seeming ill into an unmixed blessing ; especially as 

 this coccid nectar is equally as good as honey for vari- 

 ous manufacturing purposes, as the making of print- 

 ers' rolls, the flavoring of cigars, and the manufacture 

 of honey-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, 

 and make the former of no small advantage to him. 



A. J. Cook. 



of about two ounces of coal per ton of freight hauled 

 one mile, at the rate of thirteen miles per hour 

 including stoppages, and rising to five or more ounces 

 per ton per mile on grades of from fifty to seventy 

 feet. 



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 5,600,000 

 pounds, and in a distance of 3,380 miles, the con- 

 sumption of coal was 126 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 Railroad gazette very neatly says, ''Assuming 

 that paper is as efficient a fuel as coal, we have only 

 to burn a letter on board this steamer to generate and 

 utilize enough energy to transport one ton of freight 

 one mile. It is difficult to realize that so trifling an 

 act as burning a letter involves such a waste of useful 

 energy, or can have any reference to the energy suffi- 

 cient to perform a feat which, under less favorable 

 circumstances, requires a couple of horses and a 

 teamster for about half an hour." 



We may contrast with her performance that of the 

 steamship Oregon, of the Guion 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 times that of the Burgos, 

 but intended for passenger business largely, attains 

 an average speed of 17.9 knots (or 20.5 miles) per hour, 

 and burns 337 tons of coal per hour, combustion tak- 

 ing place at the rate of over 16 tons of coal for each 

 mile traversed. The cost of her coal for the voyage 

 is put at considerably over $18,000. 



The best locomotive performance in this country of 

 which there is authentic record gives a consumption 



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 tested 

 this by exploding charges of gun-cotton and dyna- 

 mite varying in weight from five to one 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, as well as possible, the stiffness of the 

 sides of a ship. Though much more work was done 

 than it is likely would ever be performed against the 

 armored side of a ship, the target was not materially 

 injured. 



In the course of these experiments it was apparently 

 shown that the point at which a charge of a high 

 explosive is ignited has an important effect upon the 

 work done, since the effects of these charges were 

 readily increased or diminished very materially, 

 according as they were ignited on the side away from 

 or adjacent to the plate; and this, too, notwithstand- 

 ing 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 must 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 ignition 

 surface remains constant. 



The gradual ignition of the charge, even in the 

 case of so violent an explosive as gun-cotton, was 

 strikingly illustrated by the fact that when twenty-six 

 pounds of wet compressed disks of that material were 

 piled upon an iron plate, and exploded from the top 

 (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 not 

 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 howitzer, and thirteen rounds from the eighty- 

 pound breech-loading rifle, and the ordinary ser- 

 vice charges of gunpowder being used in the gun. 

 Three unfuzed shells, charged with gun-cotton, were 

 fired from the eighty-pounder 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 fuze 



