318 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Ski'tember, 



degrees to the observed angle and reversing the instniment. A drawing of 

 tlie instrument accompauieJ the communication. 



" O-i setting out Curves for liailicai/s." By R. C. May, Assoc. Inst. C.E. 



The method of setting out curves proposed in this communication is founded 

 upon the 32nd I'rop. of the 3rd hook of Euclid. Jt consists in Cutting off 

 by a chord a segment of the circle to be described, and then finding any 

 number of points in the curve by means of a reflecting instrument, which is 

 set so as to reflect the angle in that segment. 



The instrument which has been adapted by the author for this operation, 

 consists of two plane mirrors, the upper one being fixed vertically upon a 

 disc of brass, and the lower one fastened to an arm wliich turns upon its cen- 

 tre, and permits the tw o mirrors to be set at any angle with each other ; the 

 arm can be fixed by a clamp screw. In tlie case surrounding the inirrors are 

 two holes, for admitting light, and between them is the sight hole, placed so 

 as to bisect the angle formed by tlie mirrors. From the underside at the 

 centre of the instrument is suspended a slender wooden rod, with a pointed 

 end, weiglited with lead. 



Angles are taken with the instrument in the same mansier as with the bo.'; 

 sextant. To determine any point in the curve, the instrument when set fast 

 is placed in such a position that the two given oljjects coincide in the mirrors, 

 and the weighted rod being released by withdrawing a bolt, falls directly 

 beneath the centre of the instrumeut, marking the required point in the 

 curve. 



The author presented with this paper a Reflecting Instrument, and field 

 tables of chords and segments to Ije used in sclting out curves by this method.* 



March 23. — The Phesident in the Chair. 



" yin imprnnd Plank Frame, for satoing Bealn an I P/nnkn of various thick- 

 ness into any number of boards." By Benjamin Hick, M. Inst. C.E. 



The principal improvement in this machine is a novel kind of gearing for 

 producing what is usually termed the "taking-up" or "traversing motiuu" 

 of the plank during the operation of sawing. 



A revohing motion is given to two pair of coupled vertical fluted rollers, 

 by means of worms and wheels, which are worked by a ratchet wheel and 

 catch, from the crank shaft of the machine. \Vhen a plank is introduced 

 between the moving rollers and the fixed guides in the centre of the macliiiie, 

 the tendency of the motion is to draw the plank forward at each stroke, with 

 a force exactly corresponding to the degree of resistance opposed by the 

 teeth of the saw. By this means, the necessity of any other support or side 

 roller to the plank, during its progress through the macliine, is avoided, and 

 any number of planks of diflferent leugth, depth, and thickness, can be put 

 through the machine after each other, without any alteration or stoppage of 

 the work. 



Several minor improvements are introduced in the general arrangement of 

 the machine, particularly in the position of the crank shaft and connecting 

 rod, which latter is placed in the centre of the moveable frame, occupying a 

 space which has not hitherto been made use of in machines for cutting two 

 planks simultaneously ; and by carrying the crank shaft upon the framing, 

 instead of having it fixed upon a separate foundation, the construction is sim- 

 plified as well as rendered less expensive. 



The commmiication was accompanied by a working model of the machine. 



" An historical Accounl of Tfood Sheathing for Shijis." By J. J. Wilkin- 

 son. 



This communication commences with the earliest history of naval archi- 

 tecture, the diff"erent modes of constnietion, and the precautions taken for 

 the preservation of the vessels from the attacks of marine animals. 



A very early instance of extraordinary attention to the preservation of the 

 bottom of a vessel appeared in a galley supposed to have belonged to the Em- 

 peror Trajan, a. d. 98 to a. d. 117, which was found in the fifteenth century 

 in the lake Hcmorese (or Lago Riccio), in the kingdom of Najiles, and was 

 weighed after it had probably remained more than 1300 years under water; 

 it was doubly planked with pine and cypress, coated with pitch, upon wliich 

 there was a covering of linen, and, over all, a sheathing of lead fastened with 

 niiils of brass or cnjiper; the timber was in a perfectly sound state. 



In the reign of Henry VIII. large vessels had a coating of loose animal hair 

 attached with pitch, over which a sheathing board of about an inch in thick- 

 ness was fastened " to keep the hair in its place." 



It is beheved that the art of sheathing vessels was early practised in China : 

 a mixture of fish oil and lime was applied ; it was very adhesive, and became 

 so hard that the worm could not penetrate it. 



The opinions of Sir Richard Hawkins, of Franf ois Gauche, and of Dampier, 

 on the practice of wood furring, arc then given at length, with extracts from 

 their journals. 



The sheathing the bottoms of ships with timber, appears to have been dis- 

 approved by these early navigators. In 1CG8, the officers of the fleet, then 

 preparing uuder Sir Thomas Allen for an expedition against the Algcrines, 

 petitioned that their vessels might not be thus encumbereil, as they were in 

 •consequence always nnable to overtake the light-sailing unsheathed vessels of 



* This paper, with enlarged fiekl tables, has been published by the Author, 

 with ;hc permission of the tcuucil cf the Insti'aitiun, to accompany the in- 

 strument. 



the enemy ; the petition was granted, upon the condition that precautions 

 should be taken by cleaning the ships' bottoms very frequently. 



In 1670 a patent was granted to Sir Philip Howard and to Major Watson, 

 for the use of milled lead sheathing ; it was not, however, introduced without 

 difficulty ; nor until an order was issued that " no oilier than milled lead 

 sheathing should he used on his Jfajcsty's ships." About the year 1700 the 

 lead was acknowledged to have failed, and wood sheathing was again intro- 

 duced. 



Numerous instances are given of the employment of wood as sheathing for 

 ships in celebrated expeditions : the ravages of the worm, the accumulation 

 of barnacles and weeds, are then described ; the qualities of the wood em- 

 ployed for sheathing in different countries, both formerly and up to the pre- 

 sent time, are examined, and the aulhor, who undertook the investigation of 

 this subject in consequence of finding how little good information existed in 

 an acccssilile form, promises the history of metal sheathing in a future com- 

 munication. 



"A Machine for bending and setting the Tire of Railway Carriage JTheelt." 

 By Joseph Woods, Grad. Inst. C. E. 



The usual mode of bending tire bars was by means of swages and hammers 

 round a fixed mandril ; after being welded, (hey were stretched on a cast-iron 

 block formed of two semicircular pieces hinged at one point, and wedged 

 apart at the opposite side ; the hoops being heated were placed on this block, 

 and by repeated blows driven into close contact with the mould. 



Much difficulty was exjicrienced in thus making up tires for large railway 

 wheels, and the present machine was constructed for facilitating tlie process. 



One end of the tire bar when heated is wedged into contact with one of 

 four segments of a circle, of the required diameter, upon a cast-iron table, 

 which is caused to revolve slowly ; the pressure of a guide whe£l at one side 

 forces the tire bar to warp round the segments, and to form the circular 

 hoop required ; its ends having been previously scarfed, are then welded 

 together. 



The tire is again thoroughly heated and placed around the four segments, 

 which slide radially on the table, and are then simultaneously forced outwards 

 by a motion of the centre shaft. 



' The tire being slightly chilled, and assisted by the swage and hammer, 

 soon adapts itself to the segments, and forms a circular hoop instead of two 

 semi-circles irregularly joined at their points of contact, as by the old system ; 

 it is then ready for being chucked on the lathe, and bored out before shrink- 

 ing on the wheel. 



It is apparent that a machine of this desciiption becomes applicable to 

 tires of any diameter, by having three or four sizes of segments adapted to 

 the table. It is found to diminish the manual labour, .and to prepare the tire 

 more accur.itely than by the usual process. 



A model of the machine, and a detailed drawing of the several parts, ac- 

 companied the communication. 



" On the improvement of the Roads, Rivers, and Drainage, of the Counliet 

 of Great Britain:' By Robert Sibley, M. Inst. C. E. 



The author had on a former occasion drawn the attention of the Institution 

 to the subject of a Bill before Parharaent, " for the better regulation and 

 general improvement of the Drainage of the Country ;" and at the same time 

 pointed out the course pursued by the magistrates of the County of Middle- 

 sex, in procuring with his professional assistance an accurate account of the 

 Rivers, Bridges, &c., hoping that it might lead to similar surveys in other 

 counties. 



In tlie present communication he investigates the nature of the works 

 which each county may be expected to undertake, and the means of accom- 

 plishing them economically, so that real public benefit may accrue. 



The objects principally requiring the attention of the county magistrates, 

 he considers to be. First— Facility of intercourse by the improvement of the 

 roads, bridges, rivers, and canals. Secondly — Protection from injury by the 

 passage of the waters from or through tlie county ; and Thirdly — The removal 

 of causes tending to vitiate the atmosphere, or to render unwholesome the 

 water used for the support of human life. 



All these points, which do not appear to have been fully comprehended in 

 the Sewage Acts, are examined at length, and suggestions are offered for their 

 regulation, with examples of the effecls resulting from their neglect. 



The advantage of placing the water-courses of the country generally under 

 a well regulated system of management, is insisted upon as the most efl'ectual 

 mode of guarding against tlie destruction of property, and not unfrequently 

 of human life, wliich ensues from the efl^ects of suddeu inundations, such a3 

 have recently occurred in the county of Middlesex. 



March 30. — The President in the Chair. 



" Description of a new Universal Photometer." By Dr. Charles SckafhaeutI 

 of Munich, Assoc. Inst. C.E. 



The inadequacy of the photometric instruments invented by Pictet, Rum- 

 ford, and others, is universally acknowledged. The bromide of silver, as used 

 by Sir John Ilerschell, although extremely sensitive, is only slightly aftected 

 by artificial light. 



' These cinumstanccs induced the author to complete the present instru- 

 ment,* which he contemplated about twelve years since. 



" The instrument was coi.structe.l by Mr. E. M. Clarjie, 428, Strand. 



