NEW YORK, AUGUST 17, 1889.

Scientific American Supplement. Vol. XXVIII., No. 711.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.


TABLE OF CONTENTS.
PAGE.
I.[AGRICULTURE.—How to Raise Turkeys.—A collection of hintsand suggestions on the raising of the delicate fowls, so often thecause of trouble to farmers.]11364
[Pear Duchesse D'Angouleme.—The history of the famous peartree, with hints as to its culture and general treatment.]11362
II.[BIOLOGY.—Development of the Embryo.—A note of some interestingbiological researches.—By Prof. Preyer, of Berlin.]11365
[The "Hatchery" of the Sun Fish.—A curious incident in thelife history of the common sunfish.—1 illustration.]11363
III.[CHEMISTRY.—On Allotropic Forms of Silver.—By M. CareyLea.—A continuation of this paper, containing one of the mostimportant researches in the history of silver, with statement ofinteresting results attained.]11361
[On the Occurrence of Paraffine in Crude Petroleum.—A valuablecontribution to the history of paraffine, with reference to petroleumand ozokerite.]11361
[Turpentine and its Products.—By Edward Davies.—A resumeof the work done by chemists in the turpentine products.—Thedifferent compounds produced therefrom.]11361
IV.[ELECTRICITY.—Electric Lighting at the Paris Exhibition.—TheOerlikon works.—A very exhaustive exhibition of electric apparatusdescribed and illustrated.—12 illustrations.]11356
[Magnetism in its Relation to Induced Electromotive Force andCurrent.—By Elihu Thomson.—A most impressive paper, bringingthe obscure laws of magnetic induction within the understandingof all without the application of mathematics.—12 illustrations.]11354
[The Ader Flourish of Trumpets.—One of the curiosities intelephony from the Paris exhibition, by which sounds are transmittedto a large audience.—4 illustrations.]11358
[The Electric Motor Tests on the New York Elevated Railroad.—Abstractsof tests which were recently made of the Daft motoron the elevated railroad of this city.]11353
V.[ETHNOLOGY.—Ancient Lake Dwellings.—Interesting abstract ofwhat is known about lake dwellings, the history of their construction,and the "finds" made on the sites by archæologists.]11363
VI.[FORESTRY.—Succession of Forest Growths.—A valuable paperon forestry, treating of the evils done by man and a plea for thenecessity of intelligent treatment of our woods.]11362
VII.[HYGIENE AND MEDICINE.—Acetic Acid as a Disinfectant.—Useof acetic acid in septic medical cases as a substitute for carbolicacid and bichloride of mercury.]11365
[Counter-Irritation in Whooping Cough.—By G.F. Inglott,M.D.—Application of irritants to the skin for curing the paroxysmsof whooping cough.]11365
[On the Health Value to Man of the So-called Divinely BeneficentGift, Tobacco.—By J.M.W. Kitchen, M.D.—The evils toman and to the soil.—A formidable series of accusations wellexpressed.]11365
[Water as a Therapeutical Agent.—By F.C. Robinson, M.D.—Aninteresting resume of different applications of water in therapeutics.—Suggestionsof use for all households.]11364
VIII.[MILITARY ENGINEERING.—Gibraltar.—A history of thisimportant strategic position and of the different sieges the fortresshas undergone.]11352
[Gibraltar and Neighborhood.—A consular report on the statisticsof the famous military station.]11352
[The Defense of Gibraltar—Experimental Naval and MilitaryOperations.—Interesting series of operations recently carried outunder the shadow of the historic rock.—1 illustration.]11352
IX.[NAVAL ENGINEERING.—Clark's Gyroscopic Torpedoes.—Arecent torpedo, in which all the possible parts are made to rotate.—2illustrations.]11353
[The First Steamboat on the Seine.—The Marquis de Jouffroy'ssteamer of 1816.—1 illustration.]11353
[The Franz Josef I., New War Ship.—Details of the dimensionsof the new Austrian ship.—Her armament, speed, armor, etc.]11353
X.[PHOTOGRAPHY.—Orthochromatic Photography.—By Oscar O.Litzkow.—The last developments in this interesting branch ofphotographic art, with formulæ.]11360
[Platinotype Printing.—A description of the most advancedmethod of conducting the platinum print process.]11360
XI.[PHYSICS.—Iridescent Crystals.—By Lord Rayleigh.—An abstractof a lecture by the distinguished physicist, detailing some interestingexperiments applicable to the colored reflection observedin crystals of chloride of potash.—1 illustration.]11366
[Transmission of Pressure in Fluids.—By Albert B. Porter.—Anapparatus for illustrating the laws of transmission of pressurein fluids, suitable for lecture purposes.—1 illustration.]11362
XII.[TECHNOLOGY.—Notes on Dyewood Extracts and Similar Preparations.—ByLouis Siebold.—The recent development in thepreparation of dyewood extracts, with notes of their adulterations.]11359

THE DEFENSE OF GIBRALTAR: EXPERIMENTAL NAVAL AND MILITARY OPERATIONS.

A novel and interesting series of operations was carried out at Gibraltar a few weeks ago, with a view to test the promptitude with which the garrison of the famous Rock could turn out to resist a sudden attack by a powerful iron-clad fleet. The supposed enemy was represented by the Channel Squadron, under the command of Vice-Admiral Baird, and consisting of H.M.S. Northumberland (flag ship), the Agincourt, Monarch, Iron Duke, and Curlew. The "general idea" of the operations was that a hostile fleet was known to be cruising in the vicinity, and that an attack on the Rock might be made. The squadron left Gibraltar and proceeded to the westward, returning to the eastward through the Straits under cover of the night.

The Governor of Gibraltar, General the Hon. Sir Arthur Hardinge, issued orders for the whole garrison to stand to their arms at dawn, and subsequent days, until the attack should be made; but by his express command no batteries were to be manned, or any troops moved from their alarm posts, until the signal was given that an attack was imminent. The alarm signal ordered was that of three guns fired in rapid succession from the Upper Signal Station on the summit of the Rock, to be followed, after a short pause, by two more shots. It was a matter of complete uncertainty as to the direction from which the attack would be made.

Every detail was carefully carried out, as if the impending attack was a real affair. The telegraphic communication between the various parts of the Rock was supplemented by signalers; arrangements were made for the ready supply of reserve ammunition for all arms; and the medical authorities established dressing stations, at numerous points of the Rock, to render "first aid" to those who might chance to be numbered among the "wounded." Day broke with a "Levanter," and the heavy clouds hanging about rendered any distant view a matter of difficulty. However, before it had become actually daylight the alarm guns gave notice that the enemy had been sighted. The troops turned out with great promptitude, being all at their assigned stations in less than a quarter of an hour, and were shortly ordered to various points commanding the east side of the Rock. As day broke, the hostile ships were to be discerned steaming in single line ahead, from the northeast, along the back of the Rock, and about 5,000 yards from it. The flag ship, followed by the Monarch and the Agincourt, proceeded toward Europa Point, while the Iron Duke and the Curlew stood close in to the eastern beach, so as to engage the northern defenses of the fortress. The first shot was fired by the flag ship, shortly before six o'clock in the morning, at the southern defenses. It was replied to, in less than three minutes, by the Europa batteries, and very shortly the engagement became general. The plan of tactics employed by the squadron was that of steaming rapidly up and down, and concentrating their fire in turn on the various shore batteries. Later on, the whole squadron assembled off Europa Point, and fired broadsides by electricity as they steamed past at speed. The spectacle at this moment was a very fine one, the roar of the heavy guns of the ships being supplemented by the sharp, rapid report of the quick-firing guns, which were supposed to be sending a storm of small shell among the defenders of the Rock. The incessant rattle of the ships' machine guns was also heard in the intervals between the thundering broadsides of heavy ordnance. All the ships were, of course, cleared for action, with topmasts and yards sent down, and it is needless to say they looked exceedingly workmanlike and formidable.

The various batteries on the Rock replied with great vivacity, and the general effect produced as gun after gun was brought to bear on the ships, and the white smoke wreathed itself round the many crags and precipices of the grim old Rock, was a sight long to be remembered. The exercise afforded to both branches of the service was undoubtedly most instructive. Our illustration is a sketch by Captain Willoughby Verner from one of the batteries above the Europa Flats, at which point the governor took up his position to watch the operations.—Illustrated London News.


GIBRALTAR AND NEIGHBORHOOD.