MECHANICAL AND USEFUL ARTS. 127 



the door of the box above instead of below. The space Litherto lost 

 is therefore gained, and thus the spur sets more elegantly. 



This Eclipse spur-box may be inserted in low heels, and the spurs 

 can be more easily used. It will fit all kinds of spurs at present in use ; 

 but the patentees call attention to their registered spurs, which have 

 the plugs reversed, to suit more perfectly the action of the improved 

 spur-box. 



IMPROVED IRON MANUFACTURE. 



The President (Mr. Bidder) of the Institution of Civil Engineers, 

 in his annual address, referred to the recent great changes in the Iron 

 Manufacture, and stated that — 



The result has been that whereas the annual "make" of a blast furnace in the 

 year 1750 was only about 300 tons, now it ranges from 5000 to 10,000 tons per 

 annum, and in a few cases amounted even to 15,000 tons per annum. In reference 

 to wrought iron it was said that the plan of reversing the rolls has been consi- 

 derably extended, and occasionally a second pair of rolls is placed close to the 

 first, runniug continuously in the opposite direction, so that the iron can be rolled 

 either in coming forward or in going back. Plates 1 J inches thick by 3 feet wide 

 and 20 feet long, and plates 4-$ inches'tbiek by 3 feet wide and 15 feet long, have 

 been rolled, as well as bars up to 72 feet long. Most of the improvements in the 

 manufacture of steel have been introduced within the last half century. Cast- 

 steel bells, weighing 53 cwt. each, have been made in this country, and castings of 

 steel weighing 100 cwt. in Austria. Large plates and very heavy bars have also 

 been made of puddled steel produced "direct from cast-iron ; and, lastly, steel 

 wire, when hardened to about a deep blue temper, is found capable of carrying 

 130 tons per square inch. More than one process has been used in the production 

 of cheap steel, which has been found by recent experiments to possess nearly 

 double the strength of ordinary iron, accompanied by other valuable properties. 

 With regard to the applications of iron, a new era commenced with the construc- 

 tion of the Conway and Britannia Bridges, as the elaborate experiments made 

 prior to their construction tended to prove that previously received theories were 

 in some respects erroneous. Again, the building erected for the Great Exhi- 

 bition in 1851, from its lightness and security, called attention to the hitherto 

 undeveloped capabilities of the combined use of cast and wrought iron for such 

 purposes. 



The improvements in the artillery and projectiles of the present day, which 

 had resulted from the efforts of civil engineers, are calculated to lead to impor- 

 tant changes in modern warfare. Simultaneous with the rapid ndvance in the 

 destructiveness of weapons of offence in attack, there was a necessity for a corre- 

 sponding alteration in the means of resistance. These subjects have led to elabo- 

 rate researches and experiments for ascertaining the best qualities of metals to 

 resist the enormous strains and concussions which have to be encountered and 

 the best dispositions in which to employ them. Iron-coated ships were for 'some 

 years regarded as a probable coming necessity ; but it was not until about the 

 end of the year 1S58, that the Admiralty for the first time seriously considered 

 the subject. This resulted in the designs on which the Warrior and Uhick 

 Prince are now being constructed. The problem is one of great difficult^'. An 

 enormous weight of armour has to be added to the weights hitherto carried. At 

 the same time greater speed is demanded, and that involves increased weight of 

 engines and a larger supply of fuel. Then, again, the weight is top. weight and 

 wine-weight, which has to be carried on fine lines for speed. To reconcile these 

 conditions with the practical points in a war vessel, and to give such a ship good 

 seafaring qualities, to make her a good cruiser, and also well suited for a voyage 

 and for the probable conditions that would attach to a European war is a \n-o'- 

 blem which may well employ the professional skill of naval architects, and of every 

 member of the Institution. 



