SCIENCE.-SUPPLEMENT. 



FRIDAY, DECEMBER 31, 1886. 



SEACOAST DEFENCES. 



The two excellent and valuable articles on sea- 

 coast defences which have been placed before the 

 public within a few days of each other — the one 

 by Lieut. Eugene GriflSn of the corps of engmeers, 

 in the Journal of the military service institution, 

 and the other by Capt. F. V. Greene of the en- 

 gineers, in Scribner^s magazine — should suffice to 

 convince the most devoted advocate of a ' peace 

 policy,' and the most economical of legislators, 

 that something should be done by the authorities, 

 and that speedily, as a mere matter of insurance 

 if nothing more, to protect our defenceless sea- 

 ports. Lieutenant Griffin's paper is more techni- 

 cal than Captain Greene's, as might be supposed 

 from the fact of its being published in a magazine 

 devoted exclusiv.ely to military interests ; but 

 while Captain Greene's article is popular, it is not 

 superficial, and by a comparison of the two the 

 intelligent reader can gain an excellent insight 

 into the subject. Lieutenant Griffin summarizes 

 the arguments against coast defences under three 

 heads : 1. The navy should constitute our de- 

 fence ; 2. Torpedoes alone suffice to close any 

 channel ; 3. Earthen batteries of sufficient 

 strength can be hastily thrown up in case of 

 war. He then answers these objections by show- 

 ing that the office of the navy is not defensive, 

 but offensive : it should protect our commerce on 

 the high seas, and injure that of our enemies. 

 Moreover, fixed guns on land have many advan- 

 tages over guns on floating supports. The second 

 argument proceeds from entire ignorance of the 

 nature and object of torpedoes. They have been 

 introduced to offset the advantages gained by the 

 attacking party in the invention of the screw-pro- 

 peller. Their function is to harass an enemy's 

 ships, and prevent them from running by bat- 

 teries. Instead of being a substitute for fortifica- 

 tions, torpedoes presuppose the latter. The plea 

 that earthworks can be thrown up as rapidly as 

 need be, is shown to be equally flimsy. In winter 

 no suitable earthworks could be thrown up at all 

 in our northern states. And supposing the largest 

 available force to work day and night, it would 

 take more than a week to construct the seventy- 

 foot parapet. What this means is evident when 

 we remember that Bermuda is only seventy-one 

 hours' steaming from Savannah, sixty-six hours 



from Charleston, and fifty-eight hours from 

 New York ; that a British fleet could get from 

 Halifax to Portland in thirty-one hours, and to 

 Boston in five hours more, or from Vancouver to 

 San Francisco in ninety-six hours. Similarly a 

 Spanish fleet at Havana is within forty-five hours 

 of New Orleans. Then, as Lieutenant Griffin 

 points out, the modern theory is to make war 

 sudden, sharp, and decisive, and to make the de- 

 feated party pay all the expenses. The billion of 

 dollars which Germany exacted from France in 

 1871 would be but a fraction of what we should 

 have to pay to any hostile power that had our 

 great seaports at its mercy. 



We have on the Atlantic and Pacific and lake 

 coasts "a series of great cities contaming an 

 aggi-egate population of more than five million 

 souls, and destructible property which is carried 

 on the assessors' books with a valuation of $4,000,- 

 000,000 (and which probably has an actual value 

 of nearly twice as much), yielding annually a 

 product in manufactured goods alone valued at 

 over one thousand million dollars." Captain 

 Greene shows that every man, woman, and child 

 of this great population, and every dollar of this 

 vast accumulation of wealth, is in danger of de- 

 struction by a hostile fleet. As he puts it, the 

 problem is one of national insurance on life and 

 property. Now, the usual annual premium on 

 policies of insurance on life or property, with good 

 risks, is from one to one and one-half per cent. 

 In Captain Greene's judgment, less than half that 

 percentage, computed on the sum total of property 

 exposed, — say, $20,000,000, — expended annually 

 for six years, would give us a complete system of 

 insurance ; that is, it would suffice to erect harbor 

 defences stronger than any ships which could be 

 brought against them, or, with an expenditure of 

 $10,000,000 annually for six years, — a sum which 

 is only about three per cent of our annual appro- 

 priations for the support of the government, — 

 fully three-fourths of the lives and property on 

 our coasts could be placed out of danger. 



To these considerations Lieutenant Griffin adds 

 the teaching of history, which is that the surest 

 way to avoid war, with all its attendant ravages 

 and losses, is by so thorough a preparation that 

 no weak point is exposed to an enemy's attack, 

 and no temptation is offered to his cupidity. 



Besides dealing with the general question in the 

 way indicated, both Captain Greene and Lieuten- 

 ant Griffin discuss the various problems presented 



