502 



MEMOIR OF DANIEL TREADWELL. 



7<7 and ^g, and tlio stud Ag standinc; upon it, tlio spindle 3/ and tin- pulley 6/ also move back and 

 forth. The band on the pulle}' 6/ at the same time alternately traverses the driuu t)/ 



r,) le. 



To stop the machine when the yarn breaks, an iron rod, 2e (Figs. 1 and 2), is hung at one end by a 

 hinge-joint to the frame a a, and runs horizontally till it nearly meets the l)obbin-frame, where it is bent 

 into a sort of hook, which is drawn against the side of the yarn by a weight passing over a pulley, 4e. 

 On the rod 2e. is a fork, 2c, through which passes the main belt a (Fig. 2) that drives the machine. 

 When the yarn breaks, the iron rod with the fork drawn by the weight shifts the belt from the driving 

 pulley to the loose pulley a', and the machine stops. 



II. — See page 403. 

 REPORT OF EXPERIMENTS ON BOSTON AND WORCESTER RAILROAD. 



To Hon. Nathan Hale, President of the Boston and Worcester Eailroad Company : — 



Sir, — After a delay of several months, from the pressure of other avocations, I have completed the 

 computation from the notes of the experiments made, at your request, to determine the resistance of the 

 cars, and various other facts connected with the motion of loads over railways, and I now beg leave to 

 present to you an account of the experiments, with the results obtained. 



The experiments were ordered for the especial purpose of determining the effect of the apparatus 

 called a " Sparkcr," invented by J. F. Curtis, Esq., the object of which is to obviate the annoyance, and 

 even danger, which arise from the sparks which pass from the fire of the locomotive engine, and, falling 

 about the train of cars, often enter them and set fire to the clothes and occasion other inconveniences to 

 the passengers. The free egi-ess of the sparks from the chimney of the locomotive engine has been in 

 some degree prevented In- the application of a large cap of wire gauze over its top. It has not been 



