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THE Cn IL ENGINEER AND ARCHITECTS JOURNAL. 



M 



ARCH, 



east to west, which will show the position of the artificial branches, is 

 tlius ; the Pelusian, the Menilesian, the Bucolic, the Sebemiilic, the 

 Saitir, the Bolbitine, and (he Canopic. 



One of the earliest hytlraiilic operations to which we find allusion 

 madp, was the recovery of the site of Memphis from the water by 

 ■which it was overtlowed. This is attributed to Menes, respecting the 

 date of whose reign some diversity of opinion exists, Herodotus calling 

 him the first sovereign of Eeypt, while by Diodorus Siculus, he is 

 styled the first king of A[emphis, a view which is supported by many 

 leading moderns. According to Herodotus the river before that time 

 flowed entirely along tlie sandy mountain on the side of Libya, but by 

 Menes its course was diverted. A hundred stadia from Memphis "a 

 bank was constructed, while a canal was led between the mountains, 

 or according to some cut through them, to receive the stream. Of 

 the ancient bed the site is still to be traced ; Savary observes that it 

 may be found west of the lakes of Natroun, extending for a consider- 

 able distance. Menes is also said to have sunk a lake to the north 

 and west of Memphis, communicating with the river, which from the 

 situation of the Nile, it was impossible to eft'ect tovi-ards the east. On 

 the spot thus rescued from the water was built the city of Memphis, 

 by which Thebes was afterwards supplanted. We have here an in- 

 stance at an early period of the diversion of a large river, and the re- 

 covery of a considerable space of ground, operations requiring a degree 

 of skill in the plan, and energy in the execution which must give 

 us a favourable idea of the engineer-king, who thus founded a city and 

 a dynasty. It might at this place be a speculation whether it was not 

 to the success of this work that Menes and his followers owed their 

 lingdom and their authority, an hypothesis which if substantiated 

 would be a unique addition to the claims of the profession. Culti- 

 rated as it has been by kings and warriors, it shares this honour with 

 the law, with which the establishment of tliis new fact would give 

 another step towards an equality of privileges — many owing their 

 kingdoms to their legislation, and' acquiring tlie exercise of authority 

 by sliowing the necessity for it. Homer mentions the practice of me- 

 dicine by powerful chiefs, but this art although it may have saved 

 crowns, never seems to have gained them. We have however another 

 subject of interest to the profession to lay before them — suggested 

 also by the works of Menes. Our author informs us that even in his 

 time, when Egypt was under the dominion of the Persians, the artifi- 

 cial channel was annually repaired, and regularly preserved ; for he 

 says had the river once broken its banks, the towii of Memphis would 

 Lave been greatly endangered. The necessity for the regular preser- 

 vation of these works would undoubtedly require their being placed 

 under the care of duly appointed oflicers", the exercise of whose func- 

 tions being specially devoted to one object would lead to the formation 

 of a particular class, essentially civil engineers. The same class of 

 officers w ould also be required in other parts of the countrv, and thus 

 we may conceive the organization at the distance of two milleniums 

 and a half of a regular irattr siaal. We have here a dawning of the sys- 

 tem of a government corps of engineers, such as exists in most coun- 

 tries abroad at this moment, for tnere must have been in Egypt little 

 cpportimity for private practice when so much depended oii the go- 

 vernment. Private practitioners of engineering, although employed 

 by governments, we shall perhaps hereafter find to have spmug up in 

 Greece — so much split up in petty states, many of which would have 

 no demand for permanent oflBcers. 



A princess, whom Herodotus calls Nitocris, is said by him to have 

 floated to death a number of Egyptians. Having been appointed sove- 

 reign on the death of her brother, who had been murdered by the 

 Egyptians, to be revenged on them she had a large subterranean apart- 

 ment constructed, to which she invited a great number of those, whom 

 she knew to be the principal instruments of her brother's death, and 

 then by a private channel introduced the water of the river among 

 them, and so destroyed them. 



To Sesostvis is attributed the execution of the general system of 

 canals with which Egypt is provided, the number of which still exist- 

 ing is estimated by Savaiy at eighty, several of which are fifty, eighty, 

 or a hundred miles long, and like 'rivers. On the return of Sesostris 

 from his foreign conquests about three thousand two hundred years 

 ago, he employed the captives of the different nations in collecting the 

 immense stones which were employed in the temple of Vulcan. They 

 were also, says our author, compelled to make the vast and numerous 

 canals, with which Egypt is intersected. In consequence of their in- 

 voluntary labovu-s, continues the historian, Egypt which was before 

 conveniently adapted to those who travelled on horseback or in car- 

 riages, became unfit for both ; the canals occurring so often, and in so 

 many winding directions, that to travel on horseback was disagreeable, 

 but in carriages impossible. The iuhabitauts of the inland parts how- 

 ever benefited by obtaining a more regular supply of water for domestic 

 and agricultural purposes. 



In his next paragraph Herodotus informs us of the well known origin 

 of surveying. Sesostris made a regular distribution of the lands, and 

 assigned to each Egyptian a square piece of ground. Whoever was 

 a sufferer by the inundation of the Nile, was permitted to make the 

 king acquainted with his loss, and certain oflScers were appointed to 

 inquire into the particulars, that no man might be taxed beyond his 

 means. To this circumstance the historian assigns the origin of geo- 

 metry, and from Egjpt it was afterwards communicated to Greece. 

 Here we have the origin of surveying, and of distinct oflScers engaged 

 in its pursuit at a period according to received chronology-, about 

 13J0-IJI) years before Christ, now three thousand two hundred vears, 

 an antiquity, of which few professions are able to boast the equal, and 

 one of the many circumstances in the historv- of civil engineering 

 which show its early progress. Thebes was then the great school of 

 Egyptian learning, and wliere geometry and surveying are supposed 

 particularly to have flourished. It was perhaps to the government 

 surveyors that the care of the canals of Memphis and other places was 

 intrusted, so that then as it frequently is now, the surveyor might have 

 been the probationer to the civil engineer. We do not apologize for 

 troubling our readers with these observations, for we know that they 

 like ourselves must feel the same interest in remembering that out's 

 is no p ofession of to-day, but one which centuries ago, as now, was a 

 powerful contributor to the progress of civilization, and the well being 

 of the human race. 



FOUR AND SIX-WHEELED ENGINES. 



Sir — There is a subject connected with the question of four and 

 six-wheeled engines as to their relative advantages when traversing- 

 curves, which has not, I believe, been suflSeiently examined into ; will 

 vou allow me, therefore, through the medium of your valuable journal, 

 to call attention to it. 



It has generally been assumed, because the distance between the 

 fore and hind wheels is greater in six than in four-w-heeled engines, 

 that there must of necessity be greater danger of the former running 

 off the rails when traversing curves. 



If the engines moved with mathematical precision in the path laid 

 out for them, this would undoubtedly be the case ; but in consequence 

 of the irregularities and inequalities of the rails, and the play which 

 it is necessary to allow on this account between the wheels and the 

 rails, the motion of the engine is varied from its true direction. Any 

 person who has observed the action of a locomotive when passing 

 rapidly along the rails, will have noticed that its track is not straight 

 but partakes of a serpentine movement, tlie fore wheels going from 

 side to side in tolerably regular vibrations, and the greater tlie ve- 

 locity the greater this effect, also the less the distance between the 

 fore and hind wheels the greater this effect; for as the play is the 

 same in all cases, the -angle formed between the direction of the rails 

 and the engine during these vibrations, will depend on the distance of 

 the points of bearing ; and it is probably rn some measure attributable 

 to this effect that four-wheeled engines have been found to go off the 

 rails when travelling over straight parts, while such an accident was 

 never, I believe, known to occnr to a six-wheeled engine, unless from 

 some foreign cause. 



The distance between the centres of the w heels in the one case is- 

 about 7 feet, and in the other about 10 feet, and the play given to the 

 wheels is half an inch. The greatest obliquity, therefore, that the 

 six-wheeled engine can take up is • J of an inch in lU feet, or 1 in "240, 

 while in the four-wheeled engine it is "3 of an inch in 7 feet, or 1 in 

 16S. It would, perhaps, be too much to assume that the engine vi- 

 brated to the whole of this amount, but, to be quite on the safe side, 

 we will take half of it, in which case the sine of the angle of obliquity 

 between the direction of the engine and that of the rails will be ex- 

 pressed by :j|-3 in the six-wheeled engine, and ^ig in the foiyr-wheeled 

 engine, when travelling on the straight parts; and it will be seen that 

 this apparently slight difference gives the advantage to the six-wheeled 

 engine in all curves used in ordinary practice. 



The sine of the angle at which aii engine meets the rails on a curve 



I 

 supposing the engine to be moving mathematically true, will be r — * 



/ being the distance between the centres of the fore and hind wheels, 

 and r the radius of the curve in feet. The advantage in favour of the 

 four-wheeled engine in this respect, on curves of the same radius, 



would therefore be as „ to :— ; but to this must be added in prac- 

 2 r 2 r 



tice the angle of obliquity due to the vibratory motion of the engine: 



