302 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Nov EMBER, 



cutting till it is fiiiiilly placed in tlie embankment, we are better able 

 justly to apportion tlie quantity of labour necessary iu each several 

 department, and so to economize both time and money. 



Our autlior professes to have selected the experiments he has given 

 from a much more extensive series, and this may possibly be held as 

 an answer to our olyections, as to the limited space over wliich the 

 experiments extend, but it must be understood we are not objecting to 

 the insiiiTiciency of these experiments, for the purpose of showing the. 

 distinct periods of time occupied iu the several processes of filling, 

 tipping, and travelling; the real meagreness of the experiments, we 

 conceive, arises from the absence of all information as to the gross 

 performance of some long periods. It is obvious that with such in- 

 formation, even should the results not agree with those which might 

 be derived from calculation by the author's formulcP, these latter might 

 still be of service, as expressing the ratio of the times occupied by the 

 various details of earthwork operations, and this, we apprehend, is 

 almost the extent of what can be expected from the experiments we 

 are considering. 



TIius should we find that the calculations on being applied to any 

 particular work already executed, shall afford a less result in point of 

 performance than we actually know to have been accomplished, we 

 may still perhaps rely upon the numercial relation to each other of the 

 several times determined in the experiments, which form the basis of 

 such calculations. We may conclude that the separate times assumed 

 for filling, teaming and travelling are all too great, but that they may 

 all safely be reduced in a certain ratio : and when so reduced we may 

 be satisfied with the conclusions they establish. Thus for purposes of 

 comparison as to the amounts of labour which can most advantageously 

 be employed in the several departments of earthworks, we hold the 

 experiments in this book to be extremely useful, and we think with 

 the restriction we have laid down against applying them to establish 

 gross results, that they may be safely depended upon. 



We will now briefly describe the mode of investigation pursued in 

 this work. 



From the observations of sixteen days the author proceeds to esta- 

 blish first the rate of speed at which the wagons travel, and then the 

 time occupied in tipping each wagon, or each set of wagons, suppos- 

 ing a sulficient number of men at the teaming place to prevent unne- 

 cessary delay. His method of deriving the rate of speed is neat and 

 ingenious, and liable to less objection than actual observation on the 

 time of passing between fixed points. For instance, the time occupied 

 in "filling, removing, and tipping the wagons," as the average of 

 several experiments, on a lead of half a mile, was 55 minutes. Also 

 the time occupied in filling, removing, nnd tipping the wagons on a 

 lead of three-quarters of a mile, amounted to t)0-47 minutes. Hence 

 we have t)9'47 — 55 = 14'47 minutes for the difference between the 

 time required for filling, removing, tipping and bringing back a set of 

 wagons upon a lead of three-quarters of a mile long; and the time 

 required for filling, removing, tipping and bringing back a set of 

 wagons upon a lead of half a mile long. This difference, namely, 14-47 

 minutes is evidently the time which elapsed while the horses were 

 drawing the loaded and empty wagons backwards and forwards over a 

 quarter (jf a mile, or in fact the difference in the lengths of the leads. 



"This shows that the average speed of transit rates at 2-4U miles 

 per hour." 



We regret to be under the necessity of pointing out that the author 

 has here made an error in calculation, as may at once be verified by 

 ascertaining the rate of speed corresponding to half a mile in 14-47 

 minutes. This rate will be found equal to 2-U7, instead of 2-40 miles 

 per hour; a material difference, and one which must affect any subse- 

 quent calculations founded upon it. We believe that the rate made 

 use of by the author, namely, 2-40, is more correct in practice than the 

 other, but this tends rather to weaken our faith in the experiments, 

 since they undoubtedly, by the author's own showing, establish 2-U7 

 miles per hour as the rate of horses' speed in transporting earih. To 

 proceed, the time of tip|)ing is then found ;= 7-UG minutes, and that of 

 filling =: 19 minutes, both these being derived, independently of the 

 rate of speed, and so not affected by the error we have pointed out 

 above. 



From the data thus established, our author derives in a simple man- 

 ner, the necessary expressions for finding the number of wagon loads 

 which may be removed fron) cutting to embankment in a given time, 

 with a given number of wagons, both for constant and varying loads. 



The next section is devoted to the investigation of the causes which 

 limit the rate of progress in forming an embankment. The author 

 shows that this rate of progress is limited by the number of teaming, 

 or as he terms them shunt roads, which can be fixed at the end of the 

 embankment, and this number will of course depend upon the height, 

 top breadth, and rate of slopes of the embankment, as affording a 

 greater or less breadth to team over. The breadth occupied by each 



road, he assumes at 8 feet, so that the whole breadth available for 

 teaming over being divided by 8, will give the number of roads which 

 can be laid down. 



It will now be necessary to notice the author's hypothesis as to the 

 available breadth of the teaming or battery head! He assumes that 

 most soils will stand at a slope of li to 1, when first tipped, and as 

 most embankments are to be finally dressed off to flatter slopes than 

 this, the difference between the base for a slope of lA to 1, and that 

 for the slope to which the embankment is to be finally dressed off will 

 be so much additional breadth, which being added to the top breadth 

 will give the whole available breadth for teaming. Thus for an em- 

 bank ment 40 fe et high, slopes 2 to 1, and top breadth 3U feet, we shal 

 have 40 x 2 X 2 +30 — 40 X U X2 = 190— 120= 70 feet, the avail- 

 able breadth for teaming over in this case. 



This brief analysis contains, we believe, the elements of the author's 

 theory, as to the limits of progress in an embankment, for taking 7-07 

 minutes as the time of lipping a set of wagons, it is evident that 84-8 

 can be tipped from each shunt road in a day of 10 hours. 



The number of wagons that can be tipped per day from each shunt 

 road, being multiplied by the number of these roads, gives the total 

 number of wagon loads that can be tipped per day from all the roads, 

 and this number being multiplied again by 2i;0, the working days in a 

 year, gives the whole performance in wagon loads ]ier annum. 



The quantity in cube yards depends of course on the capacity of the 

 wagons, which varies from two to three cube yards, according as they 

 are heaped or not, and according to their build. 



Our opinion of this part of the author's work is principally influenced 

 by comparing the gross results which his calculations establish as to 

 the rate of progress, with what we know to have been the actual per- 

 formance in cases where every effort was made to get through as large 

 a quantity of work as possible. Taking the case of an embankment 

 50 feet high, slopes 2 to 1, and top breadth 30 feel, it would appear 

 by the formul<e that we have been considering, that S4b wagon loads, 

 or say (at the most moderate allowance for each wagon) ltj9G cube 

 yards per day of 10 hours, can be tipped at eich end of the embank- 

 ment. We think our author woidd be somewhet puzzled to point out 

 an instance n here even two-thirds of this amount has ever been per- 

 formed, under the circumstances we have supposed, even for a single 

 day, much less during any long continued period. 



There is some difficulty in comparing the formulae in detail with 

 actual performance, for the want of knowing the breadth of tip in the 

 latter cases. There is however one well authenticated example which 

 may be found in the evidence of Mr. Provis, on the Loudon and Brighton 

 Railways. 



We allude to his description of the great Skelmere embankment on 

 the Birmingham and Liverpool Canal, where he states, that over a 

 breadth of 60 feet, 105,000 yards were teamed in 10 weeks during fine 

 summer weather, being at the rate of 1094 cube yards per day. 



" During one month," how-ever, says Mr. Provis, " we worked double 

 gangs, beginning at three in the morning, and ending at ten at night." 

 So that this quantity reduced to days of ten hours in length, becomes 

 105,000 in 120 days, equal to 875 yards per day. It must be remem- 

 bered that Mr. Provis was here certainly not underslatmg the per- 

 formance on this work. It was his interest to show the greatest 

 possible quantity which had ever before been accomplished, and the 

 fact he relates was considered at the time, as indeed it is entitled to 

 be considered now, a wonderful and almost unexampled performance, 

 exhibiting no small share of contrivance and energy on the part of 

 those directing the operations. 



We shall only further remark that up to April 1S37, no instance 

 could be found where even 200,000 yards had been teamed into em- 

 bankment from one face in a year; whereas our author's formulcE for 

 an embankment of the dimensions last described, would lead us to cal- 

 culate taking 250 w orking days in a year, as a performance of 124,000 

 yards per annum, and this too without nightwork, but simply during 

 250 days of 10 hours each. 



The differeiice between actual experience and the results of our 

 author's experiments arises here, we conceive, principally from the 

 use of the constant 7-07 minutes as the time of tipping. This time 

 may be perfectly correct as applicable to small embankments, and a 

 few sets of wagons where there is no danger that either men, horses, 

 or wagons will ever be in each others way, but we conceive it is quite 

 inapplicable to large works, where interruptions to the regularity of 

 proceeding would inevitably be very frequent, if the wagons were 

 worked with the proper complement of labour to ensure the condition 

 that no instant of time shall be lost at the teaming place. Thus it will 

 ever be found that the theory here laid down furnishes results as to 

 gross performance, which must not be expected in practice. 



The second part of the work commence with an inquiry into the 

 effects of the lead, principally as determining the number of wagons lo 



