Ipp MR. RENNIE'S experiments ON THE FRICTION AND 



Table VL 

 Experiments on extent of surface with Metals. 



wt. 



to be 

 moved. 



Weight 



required to 



move it. 



Propor- 

 tion. 



Weight to 

 1 inch 

 of area. 



Laid flat. 



Weight _ 

 required to *i°Pp'- 

 move it. ""»• 



Weight to 

 1 inch 

 of area. 



Laid edgewise. 



Cast Iron on Cast Iron. 



Area of surface 44 inches. 



6.58 

 7.53 

 7.38 

 7.38 

 7.27 

 7.20 

 7.23 

 6.98 



5.09 



8.72 



13.10 



1.40 



5.80 



10.20 



14.50 



2.90 



Area 6|- inches. 



lbs. 



2 



3 



5 



7 



9 



11 



13 



16 



6.20 

 6.50 

 6.12 

 6.30 

 6.30 

 6.29 

 6.31 

 6.27 



lbs. 



2 



3 



5 



7 



8 



10 



12 



14 



oz. 



1.1 



8.8 

 5.3 

 1.7 

 14.2 

 10.6 

 7.1 

 3.5 



wt. 1 Weight p^ 

 to be Tequiredtoi'yl?"^" 

 moved. 1 move it. 



Weight to 

 1 inch 

 of area. 



Weight 



required to 



move it. 



Laid flat. 



"°°- ofarea. 



Laid edgewise. 



Hard Brass on Cast Iron. 



Area of surface 48 inches. 



lbs. 

 14 

 24 

 36 

 48 

 60 

 72 

 84 

 96 



lbs. oz. 

 1 14 



3 5 



4 9 



6 4 



7 12 

 9 12 



11 8 

 13 1 



7.4 



7.2 

 7.8 

 7.6 

 7.7 

 7.3 

 7.3 

 7.3 



lbs. 

 

 



oz. 



8 



12 





 4 



8 



12 







Area 7f inches. 



lbs. oz. 

 1 11 

 4 



6 



7 13 

 9 



11 



13 2 



14 8 



8.3 

 6.0 

 6.0 

 6.1 

 6.6 

 6.5 

 6.4 

 6.6 



lbs. 

 1 

 3 

 4 

 6 

 7 

 9 

 10 

 12 



oz. 

 12 



1 

 10 



3 

 11 



4 

 13 



6 



Yellow Brass on Cast Iron. 



Tin on Cast Iron. 



Area of surface 44 inches. 



5.09 



8.72 

 13.10 



1.40 



5.80 

 10.20 10 

 14.50 13 



2.90, 15 



Area 61- inches. 



Area of surface 44 inches. 



lbs. 

 2 



lbs. 



2 



3 



5 



7 



8 



10 



12 



14 



oz. 

 1.1 

 8.8 

 5.3 

 1.7 

 14.2 

 10.6 

 7.1 

 3.5 



lbs. 

 14 

 24 

 36 



48 

 60 

 72 

 84 

 96 



lbs. oz, 



2 8 



4 7 



6 



8 7 



9 13 

 12 5 

 14 5 

 16 4 



5.60 

 5.40 

 6.00 

 5.68 

 6.11 

 5.84 

 5.86 

 5.90 



jibs. 



;! 



1 



1 

 1 



2 



oz. 



5.1 



8.7 



13.1 



1.4 



5.8 



10.2 



14.5 



2.9 



Area 6f inches. 



lbs. oz. 

 2 12 

 4 8 

 6 7 



8 14 



9 13 

 11 13 

 14 5 

 16 4 



5.09 

 5.33 

 5.59 

 5.40 

 6.11 

 6.09 

 5.86 

 6.09 



lbs. 



2 



3 



5 



7 



8 



10 



12 



14 



oz. 

 1.1 

 8.8 

 5.3 

 1.7 

 14.2 

 10.6 

 7.1 

 3.5 



^From the foregoing experiments it appears that the friction of 



' Cast iron upon cast iron laid flat, varies from 6.58 to 7.53 



Cast iron upon cast iron laid edgewise, varies from 6.2 to 6.5 



Of hard brass upon cast iron laid flat, varies from 7.2 to 7.8 



Of hard brass upon cast iron laid edgewise, varies . . . . from 6.0 to 8.0 



Of yellow brass upon cast iron laid flat, varies from 6.09 to 7.22 



Of yellow brass upon cast iron laid edgewise, varies . . . from 6.1 to 7.24 



Of tin upon cast iron laid flat, varies from 5.4 to 6.11 



Of tin upon cast iron laid edgewise, varies from 5.09 to 6.11 



That the friction is nearly the same with cast iron and brass whether the load be applied on the 

 broad side or on the narrow side of the plates, although the areas of the surfaces ate to each other 

 as 6.22 : 1. 



That tin being a softer metal and more easily abraded : the friction increases when a load is ap- 

 plied above Slbs. per square inch, but remains nearly the same with the broad side as with the 

 narrow side. Generally speaking, the friction is less with the broad side than with the narrow side. 



