In presenting before you some of the salient features of modern mill construction, I have endeavored to show the various steps of progress leading up to the development of the present types of design, as well as some of the methods of construction in present use.
These various steps in advance, producing mills better suited for the purposes for which a mill is built, are not generally due to elements originating with the manufacturers, but with the Factory Mutual Underwriters, who, finding it cheaper to prevent a fire than to settle a loss, have in every manner encouraged improvements in construction, equipment, and administration, with the result of diminishing the insurance on textile manufacturing property during the last generation from two and one-half down to one-fourth of one per cent., or reducing the cost of insurance eighty per cent.
In designing any work, a careful regard should be given to precedents, remembering that a good designer must also be a good copyist.
[The Passive State of Iron and Nickel.]—E. Saint Edme.—The nickel of commerce immediately becomes passive if immersed in ordinary nitric acid. Iron, while being briskly attacked by common nitric acid, is rendered passive by contact with nickel. If steel and nickel are plunged into the acid together, the former metal is not even momentarily attacked. Nickel retains energetically a proportion of combined nitrogen, to which its passivity is due.
IMPROVED TORPEDO BOAT.
We give an illustration of the new type of second class torpedo boat which Messrs. Yarrow & Co. have recently constructed to the order of the Admiralty, and which was tried at the latter part of last year. The boat is 60 ft. long over all and 8 ft. 6 in. wide, 3 ft. shorter and from a foot to 15 in. wider than the old type of second class boats. She attained a speed of rather more than 17 knots per hour on her official trial with 4 tons on board. The speed, when light, for six runs on the measured mile was 18½ knots. The latter seems a very high speed for so small a vessel, and indeed it is a remarkable performance, but at the same time the speed of 17.031 knots on a four hours' trial with 4 tons on board is more remarkable still. It is well to note, says Engineering, in comparing speeds of torpedo boats, under what conditions as to weight carried and duration of running the trial is made. In our previous notice we referred to the manner in which this boat differs from ordinary second class boats in the manner of ejecting the torpedo; and the arrangement is well shown in the engraving. The more ordinary method of firing the torpedo from a tube or tubes, built into the hull and pointing forward through the bow, will be familiar to the majority of our readers; but here it will be seen the bow fire has been altogether abandoned, and a swiveling gun placed aft is substituted. The gun, of course, is not new; indeed, one was placed on the old Lightning, the first torpedo boat built for the English navy. That vessel was, however, a first class boat, and although not so large as the first class boats now built, was considerably bigger than No. 50, which is the official designation of the craft under notice. In the Lightning, too, the torpedo gun was placed forward, and was trained in quite a different manner to that of this second class boat. We have already commented on the offensive advantages of being able to eject the torpedo through a wide angle of range, and when going at speed, rather than having to bring the boat to a stop and fire only end on. We need not therefore recur to this point; but since our former notice appeared we have had, while on shore, an opportunity of seeing the boat steam at speed and maneuver. Our previous experience was obtained on board—a position which, in some respects, does not afford so good a point of observation as when one is at some little distance from the boat. It is certainly a remarkable sight to see the manner in which this little vessel winds among craft or round buoys, or turns circles of surprisingly small diameter. She seems to pivot on a point very near the bow, a fact which is no doubt chiefly to be accounted for by the way the deadwood is cut away aft. This allows the stream of water diverted by the unusually large rudder to swing the after part round with facility.
