The daily morning Alaskan., 1900-04-05
FLAWS IN BIG GUNS.
INTERNAL DAMAGE CAUSED eV sUo-
 cEssIvs DISCHARGES.

The sErOslve Action of Iaaamed
 Gase.~ Cause. the First Serious Ia-
 tury-Hsw the Proiectils Helps e
 Km the Gun.
 The larger a cannon the moro exten. sive are tho injuries it receives with each successive discharge. All damage done Co gun Is internal The separate action of the powder and the projectile damages the piece every time it is aimed and fired Obviously the amount of the damage depends upon the material and workmanship of the gun. Men who make big guns describe the harm done thoir pets with many intricate and puz. zling terms of a scientific turn. In ono case a gun Is damaged because the part Of the bore whic contains the powder is enlarged This happens when the metal is compressed, and it Is moro dan serous and more plainly seen if the gunners have been using wads between their explosive and their projectile.
 Then. again, cavities arc produced by the melting away of a part of the metal by the heat of combustion of the charge Cracks come from the tearing asundei of the particles of the metal At the sur face of the bore. When it is first made. crack of this particular kind is barely perceptible. but S increases each time the gun is fired Gradually it extends completely through the side of the piece Tho crack usually begins at the junction of the chamber with the bore. simply because. as guns now are this part Is not SO well supported as tho others
 Edward :. Farrow. U. :. A., is au thori;y on damage to guns, although, like all others who have studied the question. he does not agree with very many authorities on all the points to consider in the life of a cannon. Ho con- tends that borrowing or scoring produced by tho Crosiye action of infiamed gases is the great disease which attacks the very bis guns first This particular in- jury is most apparent where the current of the gas Is most rapid or at the inte- rior orifce of the vent and on the sur face of tho bo.e. directly over the seat of the prolectile. This scoring begins very early in the life of a very large gun, but it Is conceded that it does not become very important until the piece hos been discharged considerably. Lieu tenant Farrow describes this scoring as resembling the bark of an aged elm tree, the metal being eaten away into irregu- lar furrows and ridges In extreme cases. however. scoring has not killed the gun. although in some cases it has acted like a wedge and split the bore at the place attacked.
 Where the action of the projectile has ruined tho gun the damage has been done around the projectile and in front of it The elasticity of the metal and the crowding up of portions of it in front of the shot cause rebounding process. Tho proiectile. carried forward by the forco of the charge. strikes against the upper part ot tho bore; then it IS sent against the bottom and again bounds Co the top. and so on until it emergos from the piece. The effect of this bounding motion Is Co raise and de- pross the gun in it's trunnion holes. The accuracy of Gro Is diminished. and, of course. tho gun is unat for service. Bronze guns arc the worst sufferers in this way. Mortars-short and dumpy- are not affected
 To stop the bounding of the proiectile gunners wrap the shell in cloth or pa per or else shift tbe base of the mass Co bo hurled This last process Is con sidered the bes, and is done by reduc. ing the diameter of the cartridge and adding Co it's length. Projectile injury Is also caused by furrows or scratches made by rough shells or case shot Small fragments. too. break away very often from the shells and give the bore grinding and cutting process. produc- tive oi great damage.
 Enlargement of the muzzle is another serious injury produced by the projec- tile This is caused by process which seems unavoidable As the she'll leaves the piece it strikes against one portion of the bore. The resistance at the mouth being less than at any other point, the metal naturally yields and the muzzie of the cannon is elongated in a vertical direction
 Some men who ought to know say that l5O shots is the life of very big gun-a l2 or IS inch weapon. Others placo the number of shots at 100 or 500. As matter of fact. it is all gueSswork- The great Krupp gun shown at the Worlds fair and conceded Co be perfect or supposed 70 be so-has been dis charged lees than ten times. and it is now believed Co have reached its limit On the other hand. the big guns of the American battleships have passed the time allotted .hen by wise men who know guns and apparently are as good as when tested. How soon they may yield, however. Is not in the books
 Lieutenant Farrow says that very large gun should not be expected to stand more than 100 or 500 shots before it will bo necessary to open a new vent closing the old one At it's interior orihee When the gun dies-bursts-the lines of fracture are photographed. Speoi- mems of the metal are saved. Tests arc made and conclusions drawn And Un' ole sam has figured out SO many things in this same connection that bis guns nowadays are conceded to be better than those of any other maker. They live longer than the wise ones say they Ehof Chicago Times-Herald.