1840.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



343 



We will briefly take the mean vaUies of each table, together with a snm- 

 mar>' of comparison of the whole, &c. §7%? specific yraeilij of No. 1 Iron 

 at 7-093, is rather under the standard 7-207, as given by Tredgold, but above 

 the mean of the No. 1 in Messrs. Fairbairu and Uodgkinson's list, which give 

 7-032 for twelve different irons of this number. .\s Tredgold's is a general 

 one, and not the result of any particular number ; and as it will be found in 

 Anthracite Iron, as well as in Messrs. F. and H.'s results, that the No. 1 is 



bars. — I = distance in inches between supports. — tv =112 lb. — c = breadth 

 of bar. — d= depth of bar.— a =:^ defluction caused by 112 lb. 



formula. ^ ^ ^., ^ = m, or modulus of elasticity in lb. to work which lo- 



garitlims had better be employed. 



For the above formula, see Messrs. Fairbairn and Hodgkinson's report, 

 Tredgold. &c. 



§ ■■ The precise detenuinalion of the maximum and minimum specific gravity 

 of cast-iron is of importance to the Founder and Kngineer as giving llie data 

 upon which the weight of castings are estimated, and which, as stated by 

 autliois, are an unsafe guide, inasmuch as the s|iecific gravity of cast-iron 

 varies with its composition. — the way in which it is cast, the rate of its cool- 

 ing, and tlie depth of the mould, tn an extent not generilly considered ; 

 hence the diHerent specific gravities of bars cast vertical, and those cast hori- 

 zontalhj." — Mallet on Iron. See 7ih Report of British Association. 



usually a lighter iron tlian either of the Nos., tlie above may be considered a 

 near approximation to the usual irons of the same No. or quality made- from 

 coke. 



lis modulus of elasticity, the mean of which is 13970614 shows the.com- 

 parative stiffness of the metal, and is given in pounds per square inch. 



The breaking weights are given in three separate tables, the mean of which 

 makes 444 lb., 445 tt)., and •)44-j lb. respectively, which approximate in rather 

 a singular manner to each other, and must be taken as the best proof of uni' 

 furmify ai strength and texture of this number, the value of which, as com- 

 pared with other irons, stand as under : — 



Mean of 72 results upon the Ystalyfera Anthracite Iron, No. 1 444 tb. 



Mean ditto of 10 different sorts of No. 1, in Messrs. Fairbairn and Hodg- 

 kinson's list ...... 430 lb. 



being a superior strength in favour of the Anthracite Iron of about 3i per 

 cent. I regret that most of the other authorities give the breaking of 1-inch 

 bars on a very limited scale, in few instances distinguishing the different A'o.?. 

 they were made from, and broken between distances of even" variety, which 

 is an- additional objection to my offering them in the above comparison ; but 

 in a suinmarv' of a few that I found more easy to reduce, they form rather an 

 inferior value to Messrs. Fairbairn and Hodgkinson's irons. 



The following table comprises a summary of the whole of the experiments 

 made by Mr. Evans, together with the same from Messrs. Fairbairu and 

 Hodgkinson's list : — 



Summary and Comparison of the Total Mean Results from each of the Tallies, together with the same from Messrs. Fairbairn and Hodgkinson's List. 



In making a comparison of the same numbers of the Anthracite Iron, and 

 those which are comprised in the latter 47 results, the three first of the six 

 only, contained in the preceding table, must be taken, the other specimens 

 being on iron, under other conditions, containing the mixed, planed, and cru- 

 cible results, &c., a final mean of which may be taken as aliove : — 



Which taken singly, or collectively, show a superior value in every column 

 in favour of Anthracite Iron as compared with the most numerous list of 

 other makes ; and it would appear that the No. 1 is the most uniform in 

 texture, strength, &c., having the greatest fluidity, softest, and lowest specific 

 gravity, and for its strength, which is the weakest, is most to be reUed upon, 

 as far as it extends. 



The No. 2, less uniform a little in texture, and strength, fluidity, &c., but 

 of higher specific gravity, and stronger than No. 1. 



The No. 3 still less to be depended upon in the above qualities, but of in- 

 creased specific gravity and strength to the No. 2. 



The equal mixtures show a deterioration of the several Nos., compared to 

 their values separately, and the same as regards specific gravity. The same, 

 but cast from a crucible, e.xhibit an improved Ust of values, including a greater 

 specific gravity. 



The planed bars show an increased stre;igth above the same metal in the 

 black bar : this is the only specimen whose strength is increased, without the 

 , specific gravity being greater also, which must be due to the planing, and not 

 any alteration of metal, &c. 



It may be inferred from the whole of the tables, except the last, and the 

 higher specific gravity exhibited by the Iron, the greater the strength. 



IMPROVEMENT OF LOUGH ERNE, IRELAND. 



Report of the improvement of Lough Erne, for the purpose of rendering 

 Navigable for Steam Vessels, and other Craft, and for keeping the Lake at 

 a more uniform level. 



The Upper Lake extends from Belturbet to Enniskillen, and can be navi- 

 gated through the channels or sources ; that along the eastern side is 18 

 miles in length, and that on the western is about 16 miles, which are de- 

 scribed by red dotted lines on the map or chart No. 1. 



The Lower Lake extends from Enniskillen to Belleek, its north western 

 extremity, and measures about 24 miles. 



The fall from the Upper Lake at Lisgoole Abbey to the Lake at Portora 

 is only 1\ inches. This is occasioned by the Danes Eel Weirs, the bridges 

 at Enniskillen, and the shoal at Portora. 



The Upper and Lower Lakes, considered together, present a most magnifi- 

 cent sheet of water, interspersed with numerous islands, which are in geueral 

 highly cultivated j and for beauty and luxuriance of scenery cannot w ell be 

 surpassed, and forms one of the finest lines of inland steam boat communi- 

 cation in the United Kingdom, creating as it does one direct line from east 

 to west of upwards of 42 miles in extent, besides the numerous inlets to 

 every village and farm along its coasts, which may be safely calculated at 

 three times the above length — the whole of which may. when improved, be 

 navigated without the interruption of a single lock or other obstruction, so 

 that, with good steamers, the journey from Belleek to Enniskillen, Belturbet 

 and Wattle Bridge, may be accomplished in a few hours, which at present, 

 I am told, takes the boats, containing only a few tons of goods, upwards of 

 a week, besides their having to be lightened at every shoal to enable them to 



