244 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[July, 



the direction of the tunnel, an adit or heading, to carry off the water; but 

 the earth, which was sand mixed with fine particles of blue clay, was so 

 filled with water as to become a mass of semi-fluid mud, great exertions were 

 therefore necessary to overcome the water, without erecting pumps. At 

 first this was accomplished by making each horse work for 12 hours, and 

 then for 8 hours per day, allowing one hour for food and rest; as the water 

 increased it became necessary to work night and day, and the time of each 

 horse's working was reduced generally to 6 hours, and sometimes to 3 hours. 

 As all the horses were hired at the rate of 7s. per day, the author, who had 

 the direction of the works, ordered a daily register to be kept of the actual 

 work done by each horse, for the double purpose of ascertaining whether 

 they all performed their duty, and also hoping to collect a body of facts 

 relative to horse power which might be useful hereafter. This detailed 

 register, which was kept by Mr. P. N. Brockedon, is appended to the com- 

 munication. 



The author gives as a proposition, "That the proper estimate of horse 

 power, would be that which measures the weight that a horse would draw 

 up out of a well ; the animal acting by a horizontal line of traction turned 

 into the vertical direction by a simple pulley, whose friction should be re- 

 duced as much as possible." He states that the manner in which the work 

 was performed necessarily approached very nearly to these conditions ; and 

 after giving the principal dimensions of the horse gins, he analyzes each set 

 of experiments, and by taking the mean of those against which no objections 

 could be urged, he arrives at the following results : — 



The Power of a Horse working for 8 hours = 23,4 12 lb. raised 1 ft. high in 



one minute. 

 Ditto .. 6 „ =24,300 „ ditto. 



Ditto .. 4i „ =27,056 „ ditto. 



Ditto .. 3 ,. =32,243 „ ditto. 



Of these results he thinks the experiments for 6 hours and for 3 hours 

 alone should be adopted as practical guides, all the others being in some de- 

 gree objectionable. 



As a means of comparison, the following table of estimates of horse power 

 is given : — 



These are much higher results than the average of his experiments, and 

 would more nearly accord with the extremes obtained by him; but under 

 such excessive fatigue the horses were speedily exhausted, and died rapidly. 

 Nearly one hundred horses were employed, 6 they were of good quality, their 

 average height was 15 hands } inch, and their weight about 10^ cwt., and 

 they cost from 20/. to 40/. each. They had as much corn as they could eat, 

 and were well attended to. 



The total quantity of work done by the horses, and its cost, was as under : 



Registered quantitv of water drawn 104 feet, the average 



height. 28,220,800 gallons . . . . =1 28,505 tons. 



Ditto, earth 3,500 yards, 1 ton 6 cwt. per yard. . = 4,550 



Total weight drawn to the surface 



133,955 



Total cost of horse labour, including a boy to drive each 



horse .. . . .. .. .. 1,585 15 3 



Or, 2-85 pence per ton, the average height of 104 feet 

 As soon as the adit was driven, all the water was carried off by it, and the 

 works are stated to be perfectly dry. 



Remarks. — Mr. Palmer said, it should be understood, that in stating 

 33,000 lb. raised one foot high in a minute, as the measure of the power of 

 a horse, Boulton and Matt had not intended to fix that as the average work 

 which horses were capable of performing : they had taken the highest re- 

 sults of duty performed by powerful horses, in order to convince the pur- 

 chasers of their steam-engines that they received all that had been con- 

 tracted for. He had made some experiments on the amount of work per- 

 formed by horses tracking boats on canals : on the upper end of the mast of 

 the boat a pulley was hung ; over this the the towing rope was passed, with 



The horses were supplied by Mr. Richard Lewis, Folkestone, Kent. 



the means of suspending to its extremity given weights, so as exactly to 

 balance the power exerted by the horse. The results arrived at by these 

 means were so various, that he could not deduce any average conclusions ; 

 as the power exerted varied between 301b. and 1201b., the power diminish- 

 ing as the speed was increased: he thought that 2J miles was too high an 

 average estimate, and that it should not exceed 2 miles per hour. 



Mr. Field remarked that in all estimates of horse power, the speed was 

 considered to be at an average of 2A miles per hour, and all experiments 

 were reduced to that standard. 



Mr. Hawkins said, that some years since, he had made numerous inquiries 

 respecting the work done by horses in drawing upon common turnpike roads, 

 and found, that four good horses could draw an ordinary stage coach, with 

 its complement of passengers, 8 miles a-day at the rate of 10 miles an hour ; 

 that if they ran stages of 10 miles in the hour, the horses must rest one 

 day in each week : that good horses, so worked, would last only five years, 

 each horse drawing about half a ton ; he had been informed by wagoners, 

 that good horses would walk, at the rate of '1\ miles per hour, for twelve 

 hours out of the twenty-four, making 30 miles a-day, and that they would 

 continue to do such work, day by day, each horse drawing one ton, for many 

 years, provided they had been worked hard when young. 



Mr. Gravatt observed, that although there might exist some hesitation in 

 receiving these results of work actually performed, as a general measure of 

 horse's power, yet as engineers frequently required to know what could be 

 performed by horses, when employed for short periods, in works of haste or 

 difficulty, he thought that the experiments were useful, and would form good 

 data for reference. He was sorry to observe that in too many cases, an idea 

 was prevalent, that it was cheaper to work a small stock of horses to death, 

 than to keep a large number and to work them fairly ; the results which be 

 had beeti enabled to arrive at, were perhaps not a fair value of a horse's 

 work, continued for any length of time, at the best rate of economy, for 

 both the contractor and the employer. 



The President believed that however, in cases of emergency, which he al- 

 lowed did occur in engineering works, the forced system of labour men- 

 tioned by Mr. Gravatt might be tolerated, he was convinced that it was not 

 the most economical, hut on the contrary, humanity anil economy would be 

 found to go hand in hand. It would be desirable to know the average speed 

 at which the different rates of work had been performed ; this was essential 

 in order to found any calculation upon the results given. Coach proprietors 

 calculated that, at a speed of 10 miles per hour, a horse was required for 

 every mile going and returning, so that one horse was kept for every mile 

 of road. Now supposing a four-horse coach, with an average load, to weigh 

 2 tons, the load for each horse was 10 cwt.; whereas in the case of a horse 

 drawing a cart, the gross load frequently amounted to 2 tons, but the speed 

 was reduced to 2$ miles per hour, at which pace he conceived that 16 miles 

 per day might be considered a fair day's work ; this therefore was double the 

 distance with four times the load, or eight times the coach-work, but with a 

 heavier horse. The law that the quantity of work done, was as the square 

 root of the velocity, or, as the cube root of the velocity, in equal times, was 

 confined to work upon canals, or bodies moving through water. 



Mr. Uennie had tried some experiments on the force of traction of the 

 boats on the Grand Junction Canal. The towing rope was attached to a 

 dynamometer which had previously been tested by weights. The horse, al- 

 though urged at first starting, was afterwards allowed to fall into his natural 

 speed, which was 21 miles per hour on the average of 20 miles. The maxi- 

 mum speed was 4 miles, and the minimum 2 miles per hour. The dynamo- 

 meter indicated an average of 1801b., which was capable of overcoming the 

 resistance of the loaded barge of 25 tons, being in the ratio of 1-500. The 

 weight of the horse was about 11 cwt. He had also tried many experiments 

 upon a fast boat If if to him in 1833 by the late Colonel Page. These ex- 

 periments were principally made in order to ascertain the comparative re- 

 sistance of vessels moving through water at different velocities, and the 

 Grand Junction Canal afforded a convenient opportunity of undertaking 

 them. The boat was 70 feet in length, 4 feet in breadth, and drew 9 inches 

 of water. The traction indicated by the dynamometer the following re- 

 sistance : 



Miles per hour. lb. 



At 6 the resistance was 97 to 214 



7 „ 250 



8 „ 336 



4 „ 50 969 „ 411 

 4; „ 60 10 „ 375 



5 „ 70 to 75 11 j. 392 



Average 336 



One horse was employed in these Two horses were employed in these 

 experiments. experiments. 



Stakes were fixed near the margin of the canal, so as to ascertain the rise 

 and fall of the wave caused by the boat in passing; and it was observed that 

 when the boat passed with a velocity of from 4 to 6 miles per hour, the rise 

 of the wave was 5 inches, and the fall 5 inches, making a wave of 10 inches 

 in depth; and when the velocity was 11 J miles, the rise was reduced to 2} 

 inches, and the fall to 2} inches. Great difference existed in the power of 



