lo EXPERIMENTS ON THE FULTON AND THE FROUDE. 



It is to be noted that runs at less than about 0.6 full speed are with 

 reduced power; they are most interesting experimentally, especially as the 

 sequence of the points allows us to locate the curves certainly. A very 

 important series which we have not attempted to run is to vary the speed 

 at full power by increasing the resistance of the tow. Such a series of 

 experiments, with the time required for adjusting resistance to speed, might 

 profitably occupy a summer's work. 



PULLING. 



The collected result of experiments on pulling against a fixed point 

 with one hundred per cent slip of the propeller are shown by Plate 6 for the 

 Froude and by Plate 12 for the Fulton; the latter was tried pulling both 

 ahead and astern. 



On both the Froude and the Fulton propellers with smaller pitches 

 gave better results pulling ahead. On the Froude the advantage of the 

 small-pitch propeller was very striking; thus, at 7 brake horse-power the 

 pulls for the propellers having pitch-ratios of 0.8, i.i, and 1.5 were 400, 350, 

 and 300 pounds. On the Fulton the smaller pitch showed an advantage 

 but by no means so notable; thus, at 11 brake horse-power the propellers 

 having the pitch-ratios 0.8, i.o, and 1.3 gave the pulls 560, 545, and 490. 



LENGTH OP TOW-LINE. 



For aU the experiments thus far recorded the length of the tow-line 

 was constant, being 80 feet when the Froude was towing and 70 feet for the 

 Fulton. On Plates 13 and 14 results of experiments on the Fulton with 

 varying lengths of tow-line are shown ; it will be noted that these propellers 

 having pitch-ratios of 0.8 and 1.3 gave substantially the same results, as 

 indeed might be expected since the question under consideration is the effect 

 of the race of the propeller on the resistance of the tow. 



The most interesting feature of these results is the effect of length of 

 line on speed; the changes being small are to some extent covered up by 

 the lack of accuracy of our bow-log for measuring speed; nevertheless there 

 appears to be a substantial advantage from use of a long line which is best 

 brought out on Plate 1 3 . Bearing in mind that the Fulton is 30 feet long there 

 is a gain of about ten per cent in speed due to lengthening the line from 

 twice the length of the tow-boat to six and a half times the length. In this 

 comparison the pull on the tow-line gives the most positive indication of the 

 advantage of a long line; this confirms the result just quoted in terms of 

 speed as the pull diminishes about ten per cent. 



