1841.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



35T 



The advantage of the employment of auxilian- steam power, on boiird large 

 sailing ships, had been shown by tlie author in a former paper (p. 63) ; it was 

 now further exemplified by the result of the recent voyages of the " Earl of 

 Hardwiclie" and the "Vernon." 



Earl of Ilardwicke. — This vessel, of 1000 tons burthen, with one engine 

 of 30-horse power, effected the voyage from Portsmouth to Calcutta in 110 

 days, a much longer time than usual ; but still with an advantage of 29 days 

 over the " Scotia," a fine vessel of 800 tons, which sailed one week before 

 the " Ilardwicke," and arrived 22 days after her. During the voyage, the 

 " Ilardwicke" used her engine 3C-1 hours, and was propelled by it 9-lG knots ; 

 an average of nearly three knots per hour : while in a calm, with the ship 

 steady, she made five knots per hour. The total consumption of fuel was 90 

 tons. 



The '• Vernon," which sailed one month after the " Ilardwicke," made her 

 passage to Calcutta in 97 days ; passed the " Scotia," and arrived seven days 

 before her, gaining 42 days upon her during the voyage. The "Vernon's" 

 consumption of fuel was also 90 tons, but the copy of her log not being ar- 

 rived, the number of hours dming which steam was used, could not be ascer- 

 tained. 



The " India" steam ship, of 800 tons burthen, with engines of 300 horse 

 power, had not arrived at Calcutta, althongh she had been out 109 days, so 

 that the " Vernon," with only auxihary steam power, had already gained 12 

 days upon her. 



The comparison between the advantages of these two vessels, in point of 

 expense, is then fully entered into, and shows a saving of £3733 in favour 

 of the " Vernon," on a single voyage, while she gained at least 12 days upon 

 the " India," in point of time. 



This communication is accompanied by a copy of the log of the " Earl of 

 Hardwicke," and by letters from the captains of that ship and the "Vernon," 

 speaking in the highest terms of the assistance of the steam power in certain 

 parts of the voyage." 



" Description of an improved Levelling Staff, and a modification of the 

 common Level." By Thomas Stevenson. 



In enumerating the advantages of this improvement, the author passes in 

 review the difl'erent levelling instruments in general use. He describes the 

 self-reading staff as very useful, but ill adapted to the extreme accuracy gene- 

 rally necessary in the operation of levelling. — He considers the running level 

 to be equally inadequate, from the difficulty of attaining a precise coincidence 

 in the cross wires and the vane line. 



On the authority of Mr. Simms, in his Treatise on Mathematical Instru- 

 ments, he states that these evils are in some measure remedied by Mr. Gra- 

 vatts' rod, but he still considers tiiat instrument to be imperfect. He there- 

 fore caused a rod to be constructed by Mr. Adie, of Edinburgh, the vane of 

 which is adjusted by tangent screws. The range of this staff is 12' 7 feet, 

 and the graduation so perfect as to be read by verniers to the -j-oW' °f " 

 foot. On the right of the lower portion of the rod there is a screw, which, 

 on being tightened, clamps the vane, and on the opposite side is the tangent 

 screw for adjusting it. Supposing in practice that the level line strikes the 

 lower half of the rod, the vane and screw are then easily moved liy the band 

 to within \ inch of the point, and then, by means of the tangent screw, per- 

 fect correctness can be attained. 



After having sent his communication to the Institution, the author learnt 

 from the Secretary that adjusting screws had already been used in two other 

 leveUing staves by Captain Lloyd and by Mr. Bunt. He was not, however, 

 aware of this circumstance, and he considers that these instruments being 

 adapted only for scientific purposes, are hardly suitable for the ordinary use 

 of the engineer. 



Improved Level. — The author also introduced a ball and socket joint at the 

 junction of the legs of the common level, retaining at the same time the 

 parallel screw plates, and adding beneath a small sluggish spherical level. By 

 these means the surveyor is enabled to station the instrument, regardless 

 either of the inequalities of the ground, or of the inclination of the telescope 

 to the horizon. 



When in use the clamp of the ball and socket is released, and the head of 

 the level moved until the bubble shall be in the middle of the circle ; the 

 socket screw is then clamped, and the telescope brought to the absolute level 

 by means of the parallel screws. It becomes thus unnecessary to move the 

 legs of the instrument when once fixed. 



" An improved mode of Paving Streets." By Edward Lomax. 



In this communication the author proposes to remedy the danger and diffi- 

 culty of stopping or turning horses during wet or frosty weather on wood 

 pavement. His plan is, that a breadth of 2 feet 6 inches, near each side of 

 the street, should be paved with stone, for the horses to travel upon, the car- 

 riage wheels still running upon wood ; by which means all the advantages of 

 that kind of pavement would be preserved without risk to the horse. In 

 very wide streets a centre track might also be paved with stone. 



By this plan the labour of the horse would be greatly diminished, a con- 

 sideration portion of his power being now lost, because the wood pavement 

 is less favourable for the footing of the horse than for the motion of the 

 vheels. 



The author is therefore of opinion, that granite pavement for the horse to 

 travel upon, and wood pavement for tlie wheel way, would form a road on 



which the horse would work with the least loss of power, and the greatest 

 safety. 



A model of the proposed improvement accompanied the paper. 



" Specimens of Sea-weed used for sea defences." 



Mr. Macneill presented three specimens of the Sea-weed with wliich the 

 Sea Embankments are formed in some parts of Holland. — He described one 

 of the specimens in its natural state as resembling the weed which is collected 

 by the peasantry on the western and north-western shores of Ireland, and 

 used by them for bedding. — The second specimen was taken from near the 

 bottom of the embankment at Niewe Diep, the entrance of the grand canal 

 near the Helder. It was much compressed, but elastic. — The third specimea 

 was less compressed ; it was taken from the same embankment, above the 

 range of the ordinary neap tides. 



This embankment is of considerable width, and has very little slope to- 

 wards the sea : the work appeared extremely compact and solid ; he saw it 

 when a heavy sea was running in, and each action of the waves against it 

 caused a vibration throughout the whole mass — thus proving the elasticity of 

 the material when consolidated, and corroborating the Hon. Mr. Stewart's 

 description of the same effect upon the peat sod embankments, in a paper 

 shortly to be laid before the Institution. Mr. Macneill spoke with confidence 

 of the efficiency of the peat sod for sea defences, as he had used it with good, 

 effect, although at present only to a limited extent. 



The attention of the Members of the Institution was especially directed to 

 the sea embankments of Holland, as afl'ording excellent study and ample ma- 

 terials for communications for the meetings. 



On Lead Sheathing for Sliips. By J. J. Wilkinson. 



The commencement of this communication, which is the continuation of 

 the paper on the " Wood sheathing of Ships," which was read March 23rd 

 (page 318), examines in great detail the various uses to which metals were 

 put in the earliest period of which any record exists, and then it traces the 

 first .ipplieation of lead to the protection of shipping. 



There are very early instances of ships and vessels being covered with lead. 

 In the 15th century, a boat, 30 feet in length, was found in the Mediterra- 

 nean sunk in 12 fathoms water ; it was built of cypress and larch. The deck 

 was covered with paper and linen, and over all with plates of lead, fastened 

 with gilt nails ; this covering proved so impervious to moisture, that parts of 

 the interior were perfectly dry. It is supposed to have lain there above 

 1-100 years. A Roman ship was also found sunk in the Lake of \erai. The 

 hull was of larch ; bitumen had been applied to the outside, over which was 

 a coating of a reddish colour, and the whole covered with sheets of lead, 

 fastened by gilt nails. The interior had a thick coating of cement made of 

 iron and clay. The seams of the planks were caulked with tow and pitch. 



Some of the ancient domes at Ephesus were sheathed with lead, and it 

 appears that the column of Constantine at Constantinople was formerly 

 covered wifli metal. 



It is certain that lead mines were worked in Britain by the Romans ; and 

 long before the Conquest, plates of lead were used as coverings for eccle- 

 siastical buildings. These coverings being designed to endure, were of very 

 thick lead. 



Water pipes. — In 1231, water was brought from Tyburn to London in 

 pipes ; but the material of the pipes has not been ascertained. In 1285, the 

 great conduit in Cheapside was supplied with water conveyed through pipes 

 from Paddington ; these pipes are expressly stated to have been of lead. It 

 has, however, been averred, that lead pipes for conveying water were first 

 introduced by Robert Brook, in the reign of Henry the Eighth. 



Sheet lead was used in Spain and Portugal for sheathing ships, and for 

 covering the rudders, long before it %vas employed in England. It was used 

 in Holland in 1666, and at Venice in 1710. — It is probable that we are in- 

 debted to Sebastian Cabot for its introduction into England ; it is stated ia 

 his Memoirs that he first saw it used in 1514 ; be was then in the service of 

 the king of Spain, which he entered in 1512, and was appointed pilot major; 

 he afterwards returned to England, and in 1553 was named by Queen Mary, 

 " Governor of the Mysterie and Company of Merchant Adventurers, for the 

 discovery of Regions, Dominions, Islands, and Places, unknown," — Three 

 vessels were fitted out for this purpose, under the command of Sir Hugh 

 Willoughby, one of which was sheathed, or at least partly so, with thin plates 

 of lead, then first mentioned as an " ingenious invention." This expeditiOQ 

 was unfortunate — Sir Hugh Willoughby, with the crew of two of his ships, 

 being frozen to death ; one of the commanders, and his crew, alone escaped. 

 This expedition was the origin of the trade to Russia, and of the Spitzbergea 

 Whale Fishery. 



In the reign of Elizabeth a patent was granted to one Humphrey, for 

 melting lead, but was afterwards recalled, the plan not being new. 



Milled lead. — It appears that, up to about 1670, cast sheet lead was used 

 for sheathing; at that time milled lead was invented, and a patent for milling 

 lead was granted to Sir Philip Howard and Francis Watson ; by this process 

 the inequalities, as well as the defects from air holes, in the former mode of 

 manufacture, were remedied ; the whole surface was rendered smooth and 

 uniform, and the weight greatly reduced. This invention met with much 

 opposition from the plumbers, who averred that it could not be durable ; an 

 offer was therefore made on the part of the Milled Lead Company, to keep in 

 repair during 41 years all milled lead of the weight of 7 lb. per square foot, at 

 the rate of five shillings annually per each hundred pounds worth in value. — 

 One of the earliest vessels in the royal navy thus sheathed, was the Phoenix, a 



