681 



ENGINEERING, CIVIL. 



ENGRAVING. 



lever for the purpose of moving a mass of any material which exerted 

 a resistance exceeding the unassisted strength of man : by observing 

 the effects produced in operations of that nature, the laws of the 

 action of bodies on one another were gradually discovered, and 

 mechanics, the science of the engineer, arose. 



Archimedes, in addition to the title of geometer, may with justice 

 claim that of j mechanician and engineer ; and in fact he is the first 

 person who is known to have applied himsef to the cultivation of the 

 mixed mathematical sciences. Besides demonstrating the fundamental 

 property of the lever, he determined the centre of gravity in bodies of 

 certain forms, and the positions in which bodies remain in equilibrio 

 in a fluid ; and from the celebrity he acquired among the ancients by 

 the mechanical contrivances which, according to Polybius, he put in 

 practice for the defence of Syracuse, we may conclude that if those 

 contrivances were not his own inventions, they imist have contained 

 improvements upon such as had been in use before his time. 



Vitruvius wrote his treatise on architecture during the reign, as it 

 is generally believed, of Augustus. In that treatise he describes the 

 manner of building the walls and towers for fortifying towns, the con- 

 struction of temples, basilicas, theatres, and private dwellings; he 

 describes the principal military engines which were then in use ; he 

 also gives some account of machines for drawing and raising weights, 

 of engines for raising water, and of mills turned by water for grinding 

 corn. The work may therefore be considered as comprehending 

 every important object connected with engineering at the time in 

 which he lived. Now he states, in the proem to the first book, that 

 he had been appointed by the emperor to have the charge of the 

 warlike engines; and in another place, that he had designed and 

 executed a basilica at Fanum ; it is evident therefore that he united 

 in his person the character of engineer and architect ; and among the 

 ancients the profession of the former seems to have been generally 

 included in that of the latter. The ' machinarius ' was probably the 

 artificer, or the officer who superintended the civil and military 

 machines at the siege of a fortress. 



Of the national works executed by the ancients, and which are to be 

 considered as properly falling within the province of the engineer, 

 some of the first of which we have any intimation are the sewerage of 

 Nimroud lately discovered by Messrs. Botta and Flandin ; and the 

 canal uniting the Red Sea and the Nile, which, according to Pliny, 

 was begun by Sesostris, or, according to Herodotus, by Necos, the 

 son of Psammetichus, and finished by Darius the First. The canal of 

 Xerxes across the isthmus of the peninsula of Athos is another 

 example of works of this kind. The introduction of arches in works 

 of magnitude may be said to have constituted an epoch in the pro- 

 fession of the architectural engineer, as the idea of giving to blocks of 

 stone a form which would enable them to sustain themselves in 

 balanced rest by their mutual pressures, the discovery of the means 

 of arranging them on a curve surface, and the determination of the 

 magnitudes of the piers or abutments so that the lateral pressure of 

 the vault might be adequately resisted, imply a higher degree of 

 intellectual power jthan is exhibited in covering a space with a hori- 

 zontal roof. The Cloaca Maxima at Rome is probably the most ancient 

 example in Europe of this scientific construction; the dome of the 

 Pantheon, and the various arches of the Thermae and of other public 

 buildings both at Rome and in the provinces, such as aqueducts, and 

 bridges, attest the grandeur of the design, combined with purposes of 

 public utility, which characterised the works of the engineers and 

 architects who lived under the early emperors. 



Vitruvius enumerates several Greeks who had written on machinery ; 

 but from his time to that in which Italy rose again to importance 

 after the fall of the empire, little is known concerning the state of 

 engineering ha Europe. Subsequently to the last-mentioned epoch, 

 Carden, Guido Ubaldi, Valerius, and Galileo, in that country, and 

 Stevinus, Huygens, and Descartes, in the north, are distinguished as 

 cultivators of theoretical mechanics. Galileo particularly deserves 

 to be named for his discovery of the laws of motion, his application 

 of the pendulum to the measurement of time, for his theory of 

 projectiles, and his contributions to the science of hydraulics as 

 applied to engineering. From that time almost every distinguished 

 mathematician, both on the continent and in this country, has con- 

 tributed to the advancement of the mechanical sciences. 



Previous to the commencement of the 18th century the most 

 celebrated practical engineers were Brunelleschi, who built the dome 

 of St. Mary at Florence ; Peruzzi, San Gallo, and Michel Angelo, 

 who executed that of St. Peter at Rome ; Leonardo da Vinci, who 

 constructed the earliest canal-lock in Europe ; San Michseli, the supposed 

 inventor of the bastion system of fortification : and Sir Christopher 

 Wren, the architect of St. Paul's Cathedral. 



In Holland and in the north of Italy the necessity of securing the 

 low grounds against the inundations of the seas and rivers, and of 

 obtaining an inland navigation for the purposes of commerce, gave rise 

 to the cultivation of that branch of engineering which relates to 

 hydraulic constructions ; and the invention of the lock for canals is 

 sometimes said to have taken place in the latter country about the 

 middle of the 13th century. Indeed we find the profession practised 

 in those countries on an extensive scale when there was not a man in 

 England capable of undertaking the formation of a canal to drain the 

 ground. Before the reign of Charles I. it appears to have been the 



ARTS AND SCI. DIV. VOL. III. 



practice to send to Holland for an engineer when any work of that 

 nature was to be undertaken. 



But the extension of the manufactures of this country soon after 

 that period, and the consequent augmentation both of its internal and 

 foreign commerce, called forth all the energies of its inhabitants, who, 

 at length, in the works performed for facilitating the means of com- 

 municating between one place and another, and in the practice of the 

 useful arts, rose to an eminence which other nations have not been 

 able to surpass. Among the former may be mentioned the numerous 

 canals and railways which intersect the country ; the majestic bridges 

 executed in stone over the Thames ; in cast-iron over the Avon, the 

 Thames, &c. ; and those on the suspension principle at the Menai and 

 at Hammersmith. Among the men in this branch of engineering to 

 whom the nation is indebted are Brindley, Smeaton, Jessop, Telford, 

 the Rennies, the Brunels, and the Stephensons. 



The invention of the steam-engine, or rather its improvements in 

 1769, opened a new field for the talent of the engineer in the nume- 

 rous uses to which the machine became applicable. Before the time 

 of Watt it had been employed only as a pump to raise water ; but 

 this mechanician, by converting the reciprocating motion of the beam 

 into a rotatory motion, rendered it capable, not only of replacing with 

 greatly augmented energy, the power of wind, water, or horses, in 

 giving motion to machinery for the purposes required in the arts, but 

 also of serving as a first mover for propelling vessels through water, or 

 for drawing carriages over land. 



The course of education by which a student may qualify himself to 

 become an engineer, whether civil or military, must necessarily com- 

 prehend a greater extent both of the pure and physical sciences than 

 would be required for a person who is to follow any other profession. 

 It will be, perhaps for ever, a matter of question how much mathe- 

 matics should enter into a school course of engineering, and there are, 

 no doubt, some persons who contend that no more is required than 

 would serve to compute the cost of materials and the wages of labour : 

 this, and the observation of existing examples, being supposed by such 

 persons to be sufficient to enable a man to enter upon the practice of 

 the profession. It is not, however, with such a limited knowledge 

 that an engineer can be qualified to design an important work, which 

 it may be required to conduct under new and difficult circumstances. 

 Mere science certainly cannot make a man an engineer ; for analytical 

 formulae relating to mechanical equilibrium being necessarily founded 

 on the erroneous assumption that materials are perfectly hard, per- 

 fectly smooth, &c., and that the actions of bodies on one another are 

 subject to invariable laws, have no practical utility unless corrected by 

 observation and experiment. On the other hand, mere diligence in 

 observing the results of practical operations will never raise a man to 

 proficiency in the art unless he be gifted with very extraordinary powers. 

 A judicious combination of theory and practice is indispensable, and 

 such a combination can only be made by a man in whom great natural 

 talent is blended with all the aids that the sciences can afford. 



Of the military engineer it may be said that a greater knowledge of 

 the more minute and mechanical details of construction is required 

 than would suffice for the civil practitioner ; because it may happen 

 that the former is called upon to exercise his profession in some colony 

 where workmen adequately skilled in the mechanical operations may 

 be wanting. The accomplishment of the work may then become 

 impossible, should the officer not be qualified to give the necessary 

 instructions to those who are placed under his direction. 



The professions of an architect and of an engineer, as they are prac- 

 tised at present, may.be said to coincide with one another to a certain 

 extent. The members of both of them must be able to form a judg- 

 ment of the quality of the ground in which the foundations of their 

 buildings are to be laid ; they must be acquainted with the capacities 

 of different materials, wood, stone, and iron, for resisting the strains to 

 which such materials may be exposed, so that sufficient strength may 

 be obtained with a due attention to economy ; and they must equally 

 attend to the princples of equilibrium in their roofs, arches, and domes, 

 arranging the beams, bars, or voussoirs so that they may remain at rest 

 with as little strain as possible upon the connecting ties by which the 

 joint* are strengthened. But here the two professions diverge from 

 one another ; for whilst the engineer has to determine, by a process of 

 levelling, the profile of the ground on perhaps an extensive line of 

 country, for a road or a canal ; or has to determine the forms and 

 dimensions of his retaining walls, so that they may resist the pressure 

 of earth or water against them ; or, finally, to devise methods of ren- 

 dering the action of his moving powers uniform, and of transmitting 

 them through a train of machinery to the place where the effect is to 

 be produced, the architect is engaged in designing the external forms 

 and internal arrangements of edifices, in which, whether intended as 

 palaces or private dwellings, or as buildings consecrated to the service 

 of religion or of the state, architectonic beauty must be combined 

 with fitness for the purposes for which they are intended. 

 ENGLISH BLUE. [COPPER, CARBONATE OF.] 

 ENGLISH RED. [COLOURING MATTERS.] 



ENGRAVING, the art of executing designs by incision upon plates 

 of copper, steel, or other metal, or in relief upfln wood, for the purpose 

 of obtaining therefrom impressions or prints upon paper. Although, 

 in this sense of the term, the art is only coeval with that of printing, 

 it has been practised with a more limited object from the earliest 



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