MEMOIR OF DAXIKL TREADWELL. 



319 



pipe open throughout its length, but its sides being perfectly tight, and having (he several 



vertical flexures here represented; and let it be required to pass « ter, or any heavj fluid, 



" ^ ^ "' "~~ direction A to B, (lie end A being elevated the distance ah above B; ed 



through it in the 



hcin 



g a horizontal line. 



j iass 



fill the pipe to 0, displacing all the air with which the pipe, being open to the atmosphere, 



was previously full. Flowing over the curvature e in a str mi or column less than the base 



f 



contained in (h- 



peci 



descending section from e to/ This air is thus shut up, and cannot pass from the pipe in any 



direction without passing under the water, which, from its inferior 



possible- The water, continuing to How over the flexure i , rises from / 



the flexure, the same thing is repeated as to the air from g to // which took place at the flexure 



e and/; rising from h until it reaches some point, i for example, at which the sum of th< 



perpendicular heights of the ascending columns ce,f</, etc- are equal to the height of the 





That is, if we suppose the air to be unci: tic and void of weigh! : hut as this is 



column a b. 



not true in fact, the air will be condensed in a greater or less degree, according to its volume 

 and the height of the columns of water opposed to it. In consequence of this condensation, the 

 water will rise, as shown in the figure, to k and w, for example ; and the weight of th le columns, 

 being added to the effective force of the column a b, produces a rise of the water to some point \ 

 in the flexure h n. There is then a perfect equilibrium in the opposing forces, and the water can 

 flow no farther. 



"As the aqueduct at the Mill-dam was more or less bent through its whole com-, the 

 flexures being considerable at the creeks under which it passed, it appeared to me certain that 

 it was partly filled with air, and that this alone interrupted the tlow of water. On opening 

 small holes into it in several places, air rushed out in great quantity : still, however, the water 

 did not flow at the reservoir, and, as it was impossible to g«-t at the bending in evevy part of 

 the 



pipe without the labor of uncovering it wholly, this design was abandoned. 



I forcing 



pump was then coupled to the upper end of the pipe, and water which had been heated in the 



worm-tub of a distil-house in the vicinity, was forced into it. The pump was furnished with 

 a valve loaded with a weight equal to a column of water eighty feet high, and a very small 

 opening made into the reservoir at the mills, so that the water, passing slowly through the 

 whole length of the aqueduct, was there discharged. The object of this apparatus wi to pro- 

 duce an absorption of the air, by bringing it in contact, under heavy pressure, with water which 

 had parted with some of its air by being heated ; as these conditions arc known to be favorable 

 to the absorption of air by water. The pumping was continued about ten days, and the 

 quantity of water may be taken at about twenty ho meads. The pump was then taken off, 

 and the aqueduct opened into the fountain. The water was now found to flow at the r- ervoirs, 

 discharging as much as was due to the head, and continued to flow uninterruptedly." * 



0*"O 



Boston Journal of Philosophy and the Arts, Vol. II. p. 493. 



