calculated. The difference between columns (9) and (10) will give the amount of drop through the suction valves column (13) and that between columns (11) and (12) will give the drop through the discharge valves (14). Column (15) equals column (13) multiplied by 144 and divided by 62.5. Column (16) equals column (14) multiplied by 144 and divided by 62.5. The variation in the value of K is shown by plotting the value of K× A (square feet) as ordinates with pounds of water handled per second as abscissæ. This must be done for both suction and discharge. The drop through valves, varying with piston speed, is shown by plotting it against the piston speed. Assuming the area A to be one square foot the relation between K and piston speed may be shown by plotting.

A comparison of the plots of Figs. 5 and 6 shows that as the piston speed increases the value of K increases for both suction and discharge, but that the drop decreases through the discharge valves, and increases through the suction valves.

In Fig. 6, the curve showing the loss variation determines that the most economical operating speed of the pump was at full speed.

As the continual operation of any piece of machinery at high speeds-under overload, as it were-is expensive both in steam consumption and upkeep, wear and tear, it is not desirable to have the best valve operating point at speeds above the standard, normal load.

Therefore, the value of K should be made a maximum at the normal pump speed and this may be obtained by tight valves, proper type of valve, smoothing projections inside the piping and valves, and by a study of the piping. A gasket, for instance, if only partly trimmed inside will cause excessive suction losses.

Knowing, then, that K is at its maximum at normal loads, it is a simple matter to order the speeds at which an additional pump will be started to share the load. The efficient operation of the pump will save many a bucket of coal.

DISCUSSION

The Battle Cruiser

(SEE PAGE 719, WHOLE NO. 195)

CAPTAIN T. L. JOHNSON, U. S. Navy.-This article preaches temperance. Commander Eggert shows clearly that no one of either the offensive or defensive characteristics of a battleship can be developed abnormally. Too much speed means too little battery, armor, fuel capacity-one, or all, of the equally essential qualities must suffer. On the other hand, a battleship, so named because it can give battle, is our embodiment of what we consider those qualities which will enable her to face any enemy. She must be able both to give and receive lusty blows, but in the fight she must give more than she receives, and like any fighter, be it an army or a prize-fighter, she must possess the stamina in the form of protection which enables her to be in condition to deliver the knock-out blow to the weakened opponent. Foot work, alone, never wins a fight. It is most often used to keep out of reach of the opponent. Let us build battleships which show normal development over preceding types and not go in for a new style just because some other nation has been pleased to do so. We can build battle cruisers to fight battle cruisers and so far we have built battleships which need never hesitate to meet an equal number of contemporaneous battleships of any enemy.

The writer does not always appear consistent, for he first casts doubts on the efficacy of the three-gun installation and later advocates four guns in a turret. Likewise he warns of the necessity for preparing to fight at 5000 yards range, and then says dispense with all torpedoes. Torpedoes at 5000 yards ought to be right effective and it is not believed any admiral would regret having them available to use against the enemy's column at that range-no, nor at 10,000 yards, either.

Then again, passive defence against torpedo attack does not appear justified on the ground that the torpedo defense battery takes so many men. In action we do not want to use the main battery against attacking destroyers, neither is there any use in letting them attack unmolested nor escape for the lack of an efficient torpedo defense battery.

The argument in favor of abandoning the vertical echelon of turrets on battleships is logical. If the ships are not built to chase or run away why arrange the guns for either? This arrangement of guns should accompany high speed, but the advantage gained in ahead and astern fire should not be abandoned unless it can be clearly shown that the weight gained applied elsewhere more than compensates for the loss of the gun fire. The reduced height of No. 2 and No. 3 turrets should add materially to the protection and the steadiness of the gun platform.

It is hoped that new methods of gun construction will so add to the battery power in the form of higher velocities that it will be a long time. before the 16-inch gun must be supplanted by the 18-inch.

To revert to the question of speed, why is it we want none of the captured German ships? Because they have obtained speed at the expense of armor, battery, and steaming radius. If we now begin building 28-knot battleships, what are we to do with all our 21-knot vessels? Ten years hence they will nearly all be good ships and in case of war will be used. Let us continue as we have begun-build battle cruisers, scouts and destroyers for speed, but battleships, as Commander Eggert says, for the stand up and knock down fight.

1

U. S. NAVAL INSTITUTE

Change in Board of Control

SECRETARY'S NOTES

Captains W. H. Standley and J. G. Church, U. S. Navy, tendered their resignations as members of the Board of Control upon being detached from duty at the Naval Academy, and their resignations were accepted by the Board with regret on June 10, 1919. Captain W. T. Cluverius, U. S. Navy, was elected a member of the Board of Control.

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Life, regular and associate membership, 5787. New members 21: Resignations 10.

Deaths:

Lieutenant G. C. Hill, U. S. N.

Lieutenant J. R. Cruse, U. S. N.

Mr. R. L. Bacon.

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