NEW TYPE OF MINE.

Pukekohe & Waiuku Times, Volume 6, Issue 257, 9 March 1917, Page 3 (Supplement)

NEW TYPE OF MINE.

TO PROTECT COAST. AX AM ERIC AX INTENTION. MILITARY EXPERTS ENTHUSIASTIC.

A new type of submarine which had reecently been perfected by the Coast .Artillery branch of the United States Array, and which will be issued to fortd guarding American uarbours as soon as possible, was described recently by officers who have bei-n following tests of the mine. All are enthusiastic over the pessi' 1 iltics which the new weapon affords of .simplifying and making moro effective the nation's coast defences. While the mechanism of the mine is a secret, it is known that its effectiveness lie-. <n the fact that the depth of the tide and tlie strength of the current in a harbour may l>c entirely disregarded when the mine i.s planted. An automatic device inside the mine itself can be set for any desired submergence which will keep the mine at that place (usually Bft below the surface), no matter how the tide may ri-o and fall, and in spite of any drag bv the current. 'Hi's tvpe of mine can be planted in a harbour and then left alone on the bottom, controlled by the operator at the mine-field f.witchhoard in the fort. To this .-witehboard every individual mine in the field is connected by a cable. From his pest the operator can send the mine, 011 a moment's net ice, to its war position just below the .surface, lie can tell how far it has gone by a small signll device- in the casemate, a gong, which sounds a ringing note for every fo'.t upward the hidden destroyer t ravels.

"There are reallv no up-to-date textbooks on mining," said an officer yesterday who has made harbour defnico a life studv. and who is certain that in its latest submarine mine the I nited Stale-s has devised the sini] lest and most, reliable- system of mines iu the world.

"We are always Irving' I>> got .-oinetliln<r which tln* other fellow has not thought of. and tlh' scramble for rcv-ult4 jiraet ic illv amount* to .-pring models in ininsaid lie. MILITARY "MIXES I'RF>F.XT I'RnHI.rMS. ■'There nr. l two kinds if i-nl>in:irino millet), naval and mil it ni y. Ladi lias its f u nit ion, and. inasmuch as that function differs, n) eaeli kind of mine is different. The naval initio is of noee»ity smaller. It mu-t lie carried on a fighting shi|>, :.nd i- rftwn as a protect ion against attack liy tor] odo-lioat dest rovers 011 the f-I|i|> it.-eli. ''When we come to the military mine, tiie armv's xpeeialil v. we have anothel' liroM. m. Where the navy mine irs .-own in a linrrv. the ship commander knowing oiilv in a ireneial wav where the tie d li. ts. tli" nrtnv oftie, r in charge of th" mine ( ; eld car fiillv ulants the mines, airl the field i- mapped with the ntino-l care.

''Friendly shipping as well as enemy vessels must be watched. Since there is usually plenty of time and plenty of facilities for planting military mines, the mir.es themselves are larger and more powerful than those of the navy. A navv mine will carry on the average a li.Olb charge, and the military mine as high as 40. lib of explosive. "One of the most important conditions which the army faces in tlio problem of coast defence i.s reckoning on the tide in the various harbours. Along the Atlantic coast the tide varies from five to ten feet; it i.s from 10 to 12 on the Pacific C\ ast, while at the Pacific end of the Panama Canal it is from 1") to 20. Of cour.-e, you can see that a mine which is submerged at high tide at the proper depth of from five to ten feet, at the entrance to the Canal, would at high tide be down as low some times as Mft. Useless so far as coast defence is concerned. A swift- current may drag an ordinary mine about sft, and so this, too, has to be considered.

"The old method of mining has been to plant two or three rows of mines submerged at various depths so that there will always be one line at the right depth. The disadvantages of this method lie in the fact that at low tide the mines which are submerged the least are afloat and may easily be photographed by spy or IIO.TIIO airplanes. And this, when the tide has risen, the enemy fleet, will be able to sail straight through the mine-field bv compa.-s as ea-ily as one of our own vc.-scls. PUTS sllll'S VT OPERATOR S MERCY. "It is to do awav with the.-e conditions. and also to do awav with having the mines eFsarranged by the currents, flat armv engineers haw long been working to construct jn->t the sort of mine we have perfected, a mine which will automatically adjust itself to the correct submergence. " 1 here haw in en two different -sell. n:es tried; the lir.st liar, been to get some sort cf mechanical device—a coiled spring has been the mrst popular - which is released by water pressure' and raises or lowers the mine. Another melho'l has been to coastruct a small electric motor, which i.s run bv a current generated in the fort nearby, and transmitted to the mini- along a cable. "Our mine accomidi-hed jiL-t what wo have wanted it to do. It can be pulled down to thi' bottom of a harbour out o! sight of irving acrophuit.s and out. of the way if friendly shipping. With ten minutes' notie,-, or le-s. every mine can be sent up to the pr-u.er submergence, and tin life of anv rshiji venturing within it s field i- ;it the men v of tli ■ i perator." According to t!ii~ oflieer, every hari hour del cue • f< rt in the Cited States has the material and ouiiiprneiit to mine | the bar'our within t~s hours after war |in ibe'a-el. The 11.. w mints have not ' \et be ii i ,s c d.