•M4 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[November, 



of a s)iip being deternilnpd with the ordinary log, hy ascertaining how much 

 of the line, attached to the log, ran out in a given time, it was essential that 

 hnth the time and the distance should be correctly measured ; but that was 

 seldom tlie case, as the sand in the sanil-glass, which measured the time, was 

 atTected by every change in the atmosphere, and the line which measured 

 the distance was alternately wet and dry, anil being stretched unequally, at 

 diiVerent parts, it was impossible that the marks, or Unots, could remain at 

 distances winch tliey were intended to indicate. These difficulties, when the 

 vessel was going less than 8 or 9 miles an hour, might be partially surmount- 

 ed, by counting the recpnsite number of beats of a good watch, instead of 

 using tl'.e sand glass, and by actually measuring the quantity of line which 

 ran out, instead of counting the distance by the knots. Cut in heaving the 

 log at higher rates, it was difficult to prevent the log from being dragged 

 after the ship, by the friction of the reel, and whether the line was " taken 

 olT" or " paid out," there was always a degree of doubt, whether the correct 

 length had been allowed to go off the reel. It was also nearly impossible to 

 measure the time to the requisite degree of accuracy, hy the 14 seconds sand 

 glass, which was generally used at high rates. For instance, if a vessel were 

 going 14 kno:s, the quantity of line representing one mile passed through 

 t!te hand of the observer in one second of time ; and hence, in order to ob- 

 tain the speed to the eighth part of a mile, it wo\dd be necessary to measure 

 tlic interval lo the eighth part of a second. In like manner, to obtain a ves- 

 sel's speed to the eighth part of a mile, when she was going lU knots, it 

 would be necessary to measure the interval, to the sixth part of a second. 

 As these small portions of time could not possil)ly be measured hy a sand- 

 glass, persons unacquainted with the subject, would not be surprised to learn, 

 I bat Jlr. Cuitis had heard it expressed, as an opinion, by most naval otTicers, 

 and had found by his own practice, that the rate of a ship, going more than 

 10 knots, could scarcely be obtained within a mile, under unfavourable cir- 

 cumstances. As Mr. Curtis was convinced, that the difficulty of accurately 

 measuring the speed was one of the greatest causes of the discrepancies 

 which existed in the accounts of the trials of vessels, he ventured to suggest 

 an expedient " for detf rmining a vessel's velocity at any given instant," which 

 be thought would he more accurate than the common log. He proposed, 

 tliat the time which a vessel took, in passing through her own length, should 

 be measured, from which her velocity per hour could be easily ascertained 

 by proi)ortion. For this purpose be would fit, in convenient jdaces, at a 

 short (listance from either end of the vessel, two rods, one vertical and the 

 other horizontal, so that each pair, when seen in coincidence, should point 

 in a line perpendicular to the direction of the vessel's keel. He would also 

 have a buoy painted white and black, or any colours that would show well, 

 when in the water; to this he would attach a line considerably exceeding 

 t!ie length of the vessel. This buoy should be passed forward, with plenty 

 of spare line, to the bowsprit end, the end of the line being made fast abaft, 

 ready to haul it in when done with. 



Sc'ifliUnff. — Ca])tain Hosken stated, scudding well was a point of great 

 imprriance, and was entirely a seaman's question. No point required more 

 judicious management, and correct judgment, than as to when a ship could 

 nM srud longer with safety, and ought to he " hove to." He had very often, 

 in the ' Great Western,' been scudding past very fine ships of from 500 tons 

 to 1000 tons, not very deep in the water, " laying to," because they could 

 not scud with safety. There were now several steamers longer than the 

 ' Great Western,' and he had never heard, that any difficulty had been ex 

 perienced with them, on this important point. 



Mr. PiM mentioned an advantageous application of the combined power 

 of the screw and sails, which had been practised by his relations, Messrs. Pim 

 of Hull. They had adapted to two fine trading schooners, screw propellers, 

 driven by small engine power. The result of this experiment had proved, 

 that in cases where extreme speed was not an object, but in which regularity 

 was essential, this plan might he advantageously adopted, especially for com- 

 mercial purposes, in which it was requisite to combine economy and a cer- 

 tain amount of dispatch. 



Sir J. Rennie, President, after expressing to Mr. Guppy the thai.ks of the 

 meeting, for the communication which had given rise to so interesting a dis- 

 cussion, said the construction of iron sea-going vessels was a subject of pecu- 

 liar inlere-t to the Institution, as to one of its early members must be 

 ascribed the merit of their first introduction. 



The first iron steam vessel that ever went to sea was built in 1820-1 at 

 the Hiirseley iron works, near Birmingham. It was named the ' Aaron 

 Maiiby,' after the constructor, and being put tngpther in the Surrey Canal 

 Uuck, took in a cargo of rape-seed and iron castings, in the Thames, and 

 landed it at the Pont Royal at Paris without transhipment. This unique 

 voyage was performed under the command of Captain Sir Charles Napier, 

 R.N., who was largely interested in the undertaking, and devoted much lime 

 and his usiiiil skill and energy to the enterprise. The engine was put toge- 

 thcr, and was worked duiing tlie voyage, by the present Secretary of the In- 

 stitution. The propellers were the feathering paddles which were invented 

 hy the late Mr. ,lohn Oldham. Both the engine and the paddles had been 

 superseded by more perfect machinery, and the boilers had been frequently 

 renewed, hut the bull of the vessel had required hut little repair, and was 

 still at work upon the Seine, as were several other iron vessels liuilt bj Mr. 

 XIanby, about the same time, at Horseley, and at his works at Chareuton, 

 near Paris. 



The introduction of iron, as a material for ship-building, was now becom- 

 ing so general, that th< result of the great experiment, the 'Great Britain,' 



must necessarily be regarded with much interest, and next session, the Insti- 

 tution would look forward to receiving from Mr. Guppy an account of the 

 first few voyages, and, if skill and experience could accomplish them, they 

 might he considered safe in the hands of Captaia Hosken, whose success in 

 the ' Great Western' had been so decided. 



ARCHITECTURE IN GUERNSEY. 



Sir, — Having lately visited Guernsey and observed one or two pecu- 

 liarities in the church architecture of that island, 1 tiike the liberty of send- 

 ing you a brief description of them, leaving it to jou to determine whether 

 or not they are worthy of a place amongst the mass of valuable facts of 

 which your Journal is the medium of communication, and premising that 

 I do not attempt auy sort of classification, merely collecting them from notes 

 in a diary. 



1. In the town of St. Peters, there is a church of the same name, con- 

 sisting of nave, north and south aisles, transepts, tower and spire (at their 

 intersection). The southern transept projects considerably further tiian 

 the other. At the west end of the nave the arches which separate it from 

 the aisles on either side are so low as to be intercepted above their spring- 

 ing by the caps of the piers, the sides of which are then continued to the 

 paving, following the curve of those arches ; so that the piers are broader 

 at top than at bottom. 



Fig. 2. 



Fig. 1. 



Level of Paving. 



Fig. 3. 



mn 



2. Somewhere near the cenire of the island stands Calel church, consist- 

 ing of nave, chancel, north transept, north aisle, west porch, tower and 

 spire. M hat most parliculary struck me in this church was the design of 

 the four pinnacles at the base of the spire. They each consist of four small 

 rounil columns, without cap or base supporting a square mass of stone 

 which forms a base from which to spring the pyramidal part of the piuua- 

 cle, octagonal on plan. 



3. St. Martin's church is near the eastern coast, about 2 miles from St. 

 Peter's, it consists of nave, chancel, north aisle, south porch, and a toner 

 and spire, situated at the east end of the nave. 



There is a peculiarity in the section of Ibis church, viz., that the aiste is 

 mnre In/ly than the nave, the chancel being of the same height as the aisle. 

 That the least lofty division of the church is indeed the nave is attested by 

 these facts — 1. It is in the same line with the chancel — 2. The tower and 

 spire are placed over its eastern end — 3. The pulpit is situa'ed in it. 



The chancel projects no further on plan than the aisle, from which it i» 

 separated by a cuspated arch, whose iiead is uot, however, pointed but 

 round. 



It will be observed, that bolh St. Martin's and Catel churcles have only 

 one aisle, viz., a north aisle; it m^iy perhaps also be worth noticing, that 

 the ;)oor ioics in each are similar and are of a peculiar kind, resembling 

 long narrow boxes turned on one end, so as to stand perhaps about 3 feet 

 in height, the money being admitted through a small aperture in the top. 

 I remain, Sir, your constant reader, 



G. W. R. 



October 2, 1845. 



