50 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Feb. 



puish those arches wilh four fronts, called .lanns Arches, erected in mar- 

 ket-places as a shelter for buyers and sellers, and of which a very beautiful 

 specimen is still extant at Kome, in the J'orum Bmirium. 



The Greeks do not appear to have built any triumphal arches. All 

 those in Greece or Asia Minor belong to the period of the Roman domina- 

 tion. The Romans must therefore be regarded as the inventors of these 

 edifices, which, at (irst were nothing more than wooden structures raised 

 across the streets where the triumphal processions passed. These fragile 

 and temporary constructions undoubtedly supplied the original model of 

 the form and liecoraiion of triumphKl arches. The descriptions in ancient 

 authors inform us that it was usual to place musicians and men bearing 

 trophies on the top of these monuments, while the spoils of the enemy and 

 representations of battles covered the sides. Such were the nature and 

 object of the structure, that the architect was afterwards required to pro- 

 duce in solid materials calculated to endure for centuries. 



The first permanent triumphal arches were reared under the Repuhlic, 

 but they hail no pretensions to splendour. Rosini says of them : " Primo 

 rudes et simplices fuere cum priemia virtutis essent non ambitionis leno- 

 cinia. (.-intii/. litiin I. j.) The Arch of Konuilus was rudely built of 

 bricks ; that of Caniillus, of stones, almost as rough as they came from the 

 quarry. For a long time these monuments consisted merely of a semicir- 

 cular arch, surmounted by trophiis and the statue of the conqueror. Such 

 was the one which Cicero called Arcux Fnbiniius. Triumphal arches did 

 not hold any honourable rank among the monuments of art until the time 

 of the Emperors ; and it is a remarkable fact, that, notwithstanding several 

 were erected to Augustus, and very probably in his lifetime, Vitruvius 

 does not even allude to them. At a later period, when a considerable 

 number had already been erected, Pliny speaks of them as a modern in- 

 vention. 



Down to the time of the Antonines, arches generally consisted of a single 

 arcade ; but this rule was not always adhered to, as the arch built in 

 honour of Tiberius, Drusus, Hnd Germanicus, on the bridge of Saintes, in 

 tlie Department of the Lower Chareote, had two openings of equal dimen- 

 sions. This last style, though commonly and judiciously reserved by the 

 Romans for gates of towns, was also employed in the Roman arch at 

 Langres, in the Department of the Upper Marne, probably for the purpose 

 of expressing the equality of the two Gordiaus, who both received the 

 honours of a triumph at the same time. The use of three arcades, at an 

 earlier period, is proved by medals of Domitian and Trajan, relating to 

 arches no longer in e.\istence ; but we find instances of one princip-il arch, 

 with a small one on each side, for the first time in the Arch of Orange, 

 belonging to the early years of the emjiire; again, under Septimius, and 

 his successors, as well as in most of those belonging to modern times. Thus 

 we see, in accordance with the usual course of human affairs, that the 

 richness of triumphal arches increases in an inverse ratio to the merits of 

 the actions and men whose memory they were intended to perpetuate. 



The Engineer and Contractor's Pocket Book, for the Years 1847 and 1848. 

 Edited and Pubhshed by John Weale. 



This work contains a great deal of useful information suitahle to the engi- 

 neer. Besides the Standing Orders of the House of Commons and House of 

 Lords, and Acts of Parliament relative to railways passed in 1844, and for 

 constituting commissioners of railvrays passed in 1846, it also contains prices 

 fox mechanical engineering, an interesting description of the electric tele- 

 graph, numerous tables of reference, and memoranda. We recommend Mr. 

 AVeale, in a future edition, to arrange the work a little more systematically, 

 and to withdraw the " Practical and Experimental Researches on Hydraulics," 

 for the reasons stated in our review on that paper a short time since. 



HISTORY OF ENGINEERING. 



By Sir J. Rennie, President of tijf. Institotion op Civil Engineers. 



The Address of Sir John Rennie to the last year's Annual General Meet- 

 ing of the Institution of Civil Engineers, contains a most valuable and ela- 

 borate report on the progress of engineering during the past century. The 

 length of the address precludes the insertion of the whole of it at once, but 

 as from the importance of the subjects considered, it is necessary that the 

 reader should be put in possession of the whole, the report will be com- 

 pleted in successive portions without any omissions : — 



Before I attempt to point out the course which it behoves us to pursue 

 as regards ulterior proceedings, let us pause and take a retrospective glance 

 at the changes which have been efl'ected in Great Britain since the days 

 of that great man Smeaton, to whose genius and exertions Civil Engineer- 

 ing may be said to owe its establishment as a profession in this country. 

 Previous to that period (1724), Great Britain may be said, comparatively 

 speaking, to have been lamentably deficient in public works. There were 

 DO canals, railways, nor artificial harbours, or machinery, which at the 



present day would be thought worthy of the name ; and the public roads 

 were little better than mere tracks across the country. Communication 

 between towns was difiicult ; and the few wheeled carriages in use were 

 of a rude and inelKcient description. The inland commerce of the country 

 was chiefly carried on by transport on the backs of " fack horses ;" and the 

 old-fashioned term loud, so commonly in use as a measure or weight, is a 

 remnant of that custom — meaning a horse load. The luxuries, and even 

 necessaries of life, were, consequently, extremely dear and ddhcult of at- 

 tainment. Inland navigation, which was carried on in the rivers as nature 

 had left them, was both tedious and uncertain ; and this navigation, imper- 

 fect as it was, could only be adopted at times when there was sufticient 

 water, arising from floods, or other causes ; occasionally (but of this the 

 instances were very rare) rude temporary stanches, or flash-weirs, were 

 used to pen up the running water in shallow places ; these weirs, or 

 stanches, were then suddenly withdrawn, and thus the increased depth of 

 water and the current enabled the boats to float over them ; these were fol- 

 lowed by rough unwalled locks; then by short side-cuts to avoid the diffi- 

 cult places of the rivers ; in these side-cuts the pound-luck was introduced, 

 with side-weirs to enable the floods to escape, and to supply mills with 

 water, thus answering the double purposes of navigatioo and supplying 

 power for machinery. 



The above may be taken as the extent of improvement to which inland 

 navigation had arrived in Great Britain up to the middle of the last cen- 

 tury. The navigation of the ocean, depending upon the inconstant agency 

 of the winds and tides, required months, nay, years, for communicating 

 between distant quarters of the globe. The reckoning of a ship's course, 

 during a long voyage, was most uncertain ; neither chronometers, nor lunar 

 observations, nor accurate instruments for making such observations, wers 

 known. 



Steam Engine. 



The Steam Engine (to the honour of inventing which so many indlvl- 

 duals lay claim) had, in ICUS, been so far improved, and was, for the first 

 time, constructed by Savery so as to he employed as an efficient agent for 

 raising water, was brought into active operation, in 1712, by means of a 

 steam cylinder, into which cold water was injected for causing a vacuum, 

 so as to euable a moveable piston to be impelled by the pressure of the 

 atmosphere, and thus, by the intervention of a lever, to work pumps for 

 raising water ; this was further improved by Potter and Beighton (1713- 

 18). so as to become self-acting; and thus Newcomen's engine, by degrees, 

 became generally adopted for pumping water from collieries, and from a 

 few rich mines, and for supplying the metropolis with water ; but the coi>- 

 sumption and expense of fuel was so considerable that, even great as were 

 the advantages derived from its employment, still its application was very 

 limited. After Beighton, followed Leopold, Hulls, Belidor, Payne, Blake, 

 Fitzg-erald, Emerson, and others, who made various suggestions, without, 

 however, adding anything material to the engine as improved by Newco- 

 men. Potter, and Beighton. The relation between the quantity of fuel 

 consumed and the effect produced by an engine, had never been determin- 

 ed ; and knowledge was wanting for the investigation of the important 

 subject, until Black and Cavendish, in 1760-62, had made their experi- 

 ments and discoveries on the combination of heat with bodies in their solid, 

 liquid, and gaseous states. Notwithstanding the great advantages resulting 

 from the employment of Newcomen's engine, still, for the reasons above men- 

 tioned, its application was very limited ; wind and water were alone used 

 as powers for driving machinery and working mills, which were rare, and 

 only adapted for performing rude mechanical operations, such as grinding 

 corn, fulling cloth, pumping water, blowing furnaces, hammering and roll- 

 ing iron, and such other purposes as the feeble powers of human labour 

 were unable to accomplish ; and with the exception of the silk mills intro- 

 duced from Italy by Sir Thomas Lombe at Derby in 1720, and which 

 were worked by water, there was nothing in the nature of manufacturing 

 machinery. 



Engineers. 



Smeaton, born in 1724, at an early age applied his ingenious and vigo- 

 rous mind to the cultivation of philosophical knowledge and thought, for 

 the benefit of mankind. He commenced his career as a mathematical-in- 

 strument maker in 17.50; after obtaining some celebrity in the scientific 

 world by his air-pump in 1752, he took up the subject of wind and water- 

 mills, which had, up to that period, been much neglected, and soon made 

 such improvements in them as greatly increased their powers and effi- 

 ciency ; he constructed several of both kinils according to his improved 

 principles with great success, which were considered as models, and soon 

 afterwards universally followed. In 1753 he was elected Fellow of the 

 Royal Society ; in 1759 he communicated his celebrated paper (being the 

 results of his experiments in 1752 and 1753) on the natural powers of 

 wind and water to turn mills and other machinery depending on circular 

 motion, for which he obtained their gold medal. These improvements of 

 Smeaton were of manifold importance, and produced, directly and indi- 

 rectly, the most beneficial results, as they enabled a greater quantity of 

 work to be performed both by wind and water, particularly during tem- 

 perate and dry seasons ; hence, better roads became necessary to carry 

 away the increased produce of the mills; and when they were worked by 

 water on rivers, the mill-owner became interested in the improvement of 

 the navigation, and, by economising the water on Smeaton's plan, obtained 

 one-third greater result with the same quantity, thus benefiting himself as 

 well as the navigation. Windmills have been rendered still more perfect 



