The spikers should carefully avoid striking the rail with their mauls, as such carelessness often produces fracture, which sometimes causes the rail to break in two at such points, which is liable to produce derailment and serious accident.  Spike mauls should weigh not less than nine nor more than ten pounds, and should be on straight handles, not less than 3 ft. long.  After considerable use, the face of the maul will become somewhat rounded, and when this takes place it should be sent to the shop to be redressed.  The last blow on the spike should be only sufficiently hard to cause its throat to fit snugly on the rail; a harder blow will often fracture the spike in such a manner as to cause the head in a short time to break off and leave the rail unsupported at that point.  Foremen should not allow a spike to be pulled, especially in frosty weather, until it has been first struck a light blow to break the rust and loosen its hold in the wood.  The filling of old spike holes with wooden plugs is bad practice, for the reason that they will cause the spike in a short time to slip from its place; to fill the holes with sand is much better, and spikes driven in holes so filled will hold much more firmly.  The best form of spike I have seen is the curved safety railroad spike; this spike takes in the tie a position which enables it to resist the thrust of the rail against it much more effectually than the ordinary spike can possibly do.  I have seen in good condition, one of these curved spikes which was said to have been driven eight times.  The cost of the curved safety spike is more than that of the ordinary spike, but it is better made, holds the track better, and, I believe, is worth more than the difference asked for it.—­J.A.  Hall, on Construction and Maintenance of Track, before American Society of Civil Engineers.

* * * * *

THE EXPERIMENTS AT THE ANNAPOLIS PROVING GROUNDS.

The desperate war that has been waging between the gun and armor plate, ever since the period when protective plates were first applied to naval constructions, is familiar to all.  In this conflict the advantage seems to lean toward the side of the gun, the power of penetration of which can be increased to almost indefinite limits, at least theoretically, while we quickly reach the extreme thicknesses of metal that can be practically employed for the protection of ships.

So, in recent times, researches have been making upon the efficacy of armor plating, no longer in its exaggeration of thickness, but in the intrinsic quality of the metal of which it is composed.  Metallurgists have applied themselves to the work and have thus brought out various products, among which the plates called “compound,” of Messrs. Cammell & Co., have obtained a great notoriety.  These plates, formed of a true plating of steel upon a bed of soft iron, have been much in vogue in the English navy, and seemed as if they were to be adopted about everywhere.