iS/3- 



Engineering. 539 



A chemical examination of Staurolite has been undertaken by Rammels- 

 berg. Two crystals were examined — one from Brittany, and the other from 

 Pitkaranta, in Finland. 



I he occurrence of indium in zinc-blende, from several American localities, 

 has been detected by Mr. H. B. Cornwall. From Roxbury, in Connecticut, a 

 blende was obtained so rich in indium that it could be detected spectroscopically 

 by examining the raw powdered blende, without treatment with acids according 

 to Richter's method. 



Several analyses of American minerals have been published by Prof. A. R. 

 Leeds, in a recent number of " Silliman's Journal." 



A new analysis of Dcivalquitc, from Salm-Chateau, in Belgium, has been 

 recorded by M. Pisani. This is the same mineral which has been described 

 by German writers as Ardmnite. The new analysis shows 3*12 per cent of 

 vanadic acid. 



ENGINEERING — CIVIL AND MECHANICAL. 



Guns and Armour. — It is impossible to anticipate when or where the contest 

 between guns and armour will cease. No sooner has an armour-clad vessel or 

 fort been constructed, with a view to defence against the heaviest known guns, 

 than the War Department at once begins to devise a gun whose shot shall 

 pierce the thickest armour in the world. Thus there is continually going on 

 an incessant competition for supremacy between the Admiralty and the 

 War Office. The biggest gun of which we have hitherto heard is the 

 " Woolwich Infant," of 35 tons weight, which fires a 700-lb. shot with a 

 charge of no lbs. of powder; and the shot from this monster piece of ord- 

 nance could perforate the turret of the Devastation at any distance up to 

 500 yards. The armour plating of the Devastation is 14 inches in thickness, 

 but an additional 2 inches in thickness would, it is said, render the vessel 

 shot-proof against the biggest gun in the world. The War Department has 

 hitherto cautiously advanced from guns of 12 tons weight, to 18, 25, and 

 ultimately to 35 tons in weight ; but they are now said to be contemplating 

 the construction of one of 60 tons, the powder charge for which will weigh 

 200 lbs., and it will throw a shot over half a ton in weight, which will be able 

 to perforate a 20-inch turret. 



Harbours (Holyhead). — The inauguration of the harbour of refuge at 

 Holyhead, on the 19th of August last, by the Prince of Wales, marks the 

 completion of one of the finest works of this class yet completed. Between 

 the years 1835 and 1847 tne attention of Government was directed to the im- 

 portance of providing improved harbour accommodation on the coast of North 

 Wales, in the interest of the packet-service between England and Ireland. 

 For this purpose Holyhead was selected as the most suitable site ; and of the 

 several schemes proposed for that place to accomplish the required end, the 

 plan suggested by the late Mr. James Meadows Rendel was ultimately ac- 

 cepted, who, in August, 1845, was requested by the Lords of the Treasury to 

 furnish detailed plans and estimates for the new harbour, and who reported 

 thereon on the 5th of December of that year. Mr. Rendel's plan consisted 

 of a north breakwater 5360 feet in length from the coast line, and an eastern 

 breakwater about 2000 feet in length, — the two enclosing between them an 

 area of 267 acres of available water space, — and of a packet pier 1500 feet 

 long, situated within the enclosed area. The east breakwater was subse- 

 quently abandoned, as was also the proposed packet-pier, it having been sub- 

 sequently determined to carry on the packet-service in the old harbour, where 

 jetties and works have been constructed for the purpose. The north break- 

 water alone has been retained, and the new harbour has become principally a 

 harbour of refuge. As the works advanced, however, it was found that, not- 

 withstanding the abandonment of the new harbour as a packet station, which 

 increased its capacity as a harbour of refuge, it was likely to prove too small 

 even for refuge purposes. The Lords of the Admiralty therefore decided to 

 lengthen the north breakwater by 2000 feet, and subsequently by another 



