146 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[May, 



and deep enough for barges laden with corn to sail therein ; they fall 

 into the Euphrates, and are distant from one another one parasang, 

 having bridges over them. With regard to the origin of these canals, 

 Arriaii differs from our author, as he says that the canals which ruu 

 from one to the other are derived from the Euphrates and fall into the 

 Tigris. — Strabo and I'liny oonlirm this, assigning as a reason for the 

 construction of the canals, that they are cut to receive and distribute 

 the increase of water arising from the melting of the spring snows. 



Clearchusi' whilst in tlie same district on his retreat was nnich em- 

 barrassed by meeting with canals and ditches full of water. Clearchus 

 suspected that as this was not the season to water the country, that 

 the king had ordered the waters to be let out to impede tlie Greeks 

 on their march. 



About a day's march from Babylon the Greeks made in two days a 

 march from Baljylon, eight parasangs and passed two canals, one u;>on 

 a bridge, the other upon seven pontoons. — Xenophon again says that 

 these canals were derived from the Tigris, .ind that from them ditches 

 were cut that ran into the country, the lirst broad, then narrower, 

 which at last ended in small water courses, such as were used in 

 Greece to water a kind of grain called panic. 



To the history of these canals we shall be able to derive many con- 

 tributions when we come to the works of .Strabo, riiny, and Ammianus 

 Marcellinus. The boats of the Babylonians, as described by Herodotus, 

 ■were peculiarly adapted fur the navigation of these canals. At pre- 

 sent the canals are choked up. 



BRIPCtES. — PASSAGE OF RIVERS AND CANAL= 



-PHTSCU3. 



lu the course of the expedition and the retreat, the Greeks came to 

 manv broad rivers, which in general they passed by fording, or by 

 crossing on rafts: near Uabylon they were able to avail themselves of 

 the bridges of which they mention several. On one occasion coming 

 to the Tigris'.;: thev found the river \ery deep, when a Rhodian pro- 

 posed the following plan. "I shall want," said he, " two thousand 

 leather bags — I see here great numbers of sheep, goats, oxen, and 

 asses; if these are flayed, and their skins Wown, we may easily pass 

 the river with them. — 1 shall also \v»nt the girths belonging to the 

 sumpter horses : with these I will fasten the bags to one another, and 

 hanging stones to them, let them down into the water instead of an- 

 chors, then tie up the bags at both ends, and when they arc ujion the 

 water, lav fascines upon them, anil cover them with earth. Every 

 bag will bear up two men, anil the fascines and earth will prevent thera 

 from slipping." The generals considered this proposition ingenious, 

 but were afterwards enabled to get out of their dilliculties another way. 



In the First Book bridges are mentioned over four canals near Baby- 

 lon, each a hundred feet long; in the Second Book we have a reference 

 to another; and in the same book we find it stated that over the river 

 Physcus, one hundred feet broad, a bridge was placed communicating 

 with a large and populous city called (Jpis. When Clearchus came 

 among the flooded canals, he passed them by temporary bridges made 

 of palm trees. 



WALL OF MEDIA. 



In the Second Book we have mention of the Wall of Media, which 

 was built with burned bricks laid in bitumen: being twenty feet in 

 thickness, one hundred feet in height, and as it was s.iid twenty para- 

 sangs in length, and not far from Babylon. 



CITIES AND FORTS. — ^WALI-S, — LARISsA. — .MESPILA. 



Larissa or Resen is described in the Third Book as a large unin- 

 habited city near the Tigris, anciently inhabited by the Medes, the 

 ■walls of which were five-and-twenly feet in breadth, one hundred in 

 beigiit, and two parasangs in circuit ; all built w ith brick, except the 

 plinth, which was of stone, and twenty feet high. One day's march 

 fi-om thence the (ireeks came to a large uninhabited castle near a 

 town, called Mespila, formerlv inhabited also by the Medes. The 

 plinth of the wall was built of polished stone fuU of shells, being fifty 

 leet in breadth, and as many in height. Upon this stood a brick wall 

 fifty feet also in breadth, one hundred in height, and six parasangs in 

 circuit. 



PYRAMID OF LARISSA. 



Close to the city of Larissa, says Xenophon, stands a pyramid of 

 stone, one hundred foet square, and two hundred high, which seems to 

 have been hollow. 



GREEKS. 



The observations of Xenophon as to Greek engineering we extract 

 from his history of the affairs of Greece. In his Expedition of Cyrus 



however he alludes to the mole of the harbour of Bvzantium, and to 

 his forcing the Ionian Greeks to repair the roads through their cities 

 preparatory to the march of his army. 



(iUAREIES OF IH£ PIRiElTS. 



The quarries of the Piraeus ("Book 1st,") were in Xenophon's time 

 wrought by Synicusan prisoners, who were confined there, and who 

 made their escape by digging themselves a passage through the rock. 



CAPTIRE OF MAVriNEA. 



Ill the course of the Peloponnesian war (Book 5th) Maiitinea was 

 captured by tlie .Spartans under Agesipolis. Besides the usual works 

 of digging a trench, and constructing a wall, he dammed up the river, 

 which was a large one, running through the city. The channel being 

 thus dammed up, the water swelled above the foundations of the houses 

 and of the (rity vialls. The lower brickwork (being probably of raw 

 bricks) was soon rotted by the wet, and shrank under the upper build- 

 ings, by whiidi means the city walls cracked, and afterwards were 

 ready to tumble. For some time they underpropped them with tim- 

 ber, and made use of al! their art to keep them from falling. The 

 Mantiuians ultimately consented to demolish their walls. 



ERID&E or SELLA SIA. 



A bridge is mentioned in the Sixth Book, at Sellasia leading to 

 Sparta, but no description is given of it. 



DOCKS OF GYTHEUM. 



The docks of the Spartans (Book Gtb,) were at Gytheuni. 



PUBLIC INXS AT ATHENS — SHOPS, &C. 



In his pamphlet on the revenue of Athens, Xenophon alludes to the 

 l)ublic inns for the use of strangers, he also recommends the builduog 

 of greater numbers of shops, warehouses and exchanges for common 

 retailers, relying upon it as a good means of revenue. 



REPAIRIXG riBUC BUILDINGS BY CONTRACT. 



Xenophon also in this pamphlet slightly alludes to the custom which 

 the (jreeks had of letting out the building and repair of their temples 

 to private undertakers also mentioned br^ Atheneeus and Herodotu=, 

 B. :., C. (i-2. 



I L'O'jk 2nil. 



Book 3rd. 



DOCBLi: OFFSET PLOTTING SC.VLE. 



T/ie SHrfr Medal was pivsented liji the Society of Arts to Mr. James G. 

 J'tslin, 30, Grafton Street, Gower Street, for his Offset Plotting Scale for 



the use of Civil Engineers and Surreijors. 



The Double Offset Plotting Scale consists of two perfectly parallel gradu- 

 ated scales, whose distance is equal to the length of the oft'set scale which 

 runs on rollers between them. The parallel scales and the offset scale are 

 graduated to suit t!ie views of the user. Tlie pieces connecting the ends of 

 the double scale are hollowed out to receive weights, armed with points to 

 enter the paper, which hold the instrument in its place, and prevent its bebig 

 shifted while in use ; and from the centre of each of these connecting pieces 

 jirojects an index ; the points of these indices and the zero of the offset scale 

 being always in the same straight line, which is, of course, the line from 

 which the offsets arc to be measured. 



BRIDGE OF THE HOLY TPaNITY. 



I\- coiislnicling the curve of the arches of the bridge of the Holy TrinitA', 

 according to the geometrical solution given in the last ninuherof the Joarual, 

 1 found the arcs Ell, HII, make an angle at II, in consetpiencc of the centres 

 CI not being in a right line with the point of intersection II. This fault 

 must have been overlooked by the author of the paper, and I take the liberty 

 of thus troubling thee in order that the error may he corrected. May I also 

 .ask what advantage an arch upon this construction woidd have over a semi- 

 elliptical one of the same versed sine (besides the simpUcity of striking ont 

 the curve) ? 



I am, respectfully, 



Ine.\j'ertvs LottrrsDi. 



^'.atli, ith month, I2lh day, 1841. 



