MARLING ESTIMATES. 301 



of ploughing. If desiring more perfect exactness, it could be easily 

 obtained by adding to or deducting from one of the dimensions the 

 necessary fraction of a yard. 



Heaped bushels of loose marl, as measured separately, do not 

 vary much from the same number of even bushels, as compressed 

 in a cart body, by its own weight, and by the travel to tho field. 

 I find reference to bushels more convenient than to cubic feet. But 

 if preferred, the same desired results may be reached by using 

 Table I., and cubic feet as the measure instead of bushels. 



The measuring of marl, in a half-bushel measure, for the purpose 

 of determining larger quantities, is but a rough and uncertain 

 method, which is only to be relied on when the average is taken 

 of many such trials. The irregularity of the lumps of marl, when 

 first dug, and the uncertainty of the degree of heaping of the 

 measure, may make even the same kind and condition of marl 

 appear to vary in quantity and weight, by 6 or 8 pounds in the 

 bushel. Besides other smaller trials, at other times, I made the 

 following measurements and weighings of a single load of marl, of 

 which the report may be of use for comparison : 



A load of marl, just dug, was thrown into the cart, as usual, by 

 shovels. The heaping of the load rose 7 inches, in the middle, 

 above the top of the cart body. (Lumpy and moist marl may be 

 heaped much higher than dry and pulverized.) This was about 

 the ordinary degree of heaping, when the roads were in the firmest 

 state. The load was drawn to my barn, 2000 yards of the route to 

 the field, and there measured by the half-bushel, heaped, and each 

 separate measure weighed. The weights varied from 49 to 56 % 

 Ibs. of the 39 half-bushel measures (19 i- bushels) which the load 

 filled. The whole load weighed 2050 Ibs., and the average weight 

 of the heaped bushel was 105.16 Ibs. This marl was of the kind I 

 have altogether used at Marlbourne [to 1850] compact clayey 

 marl, partly in lumps, moist naturally in its bed, but free from any 

 other water. 



The inside dimensions of this two-mule cart body were these : 

 Average of length, inches, 60.87 



" width, 40 



- depth, " 15.16; 



which make 21.36 cubic feet, or 17.12 even bushels of capacity. 

 (A bushel contains 2150.6 cubic inches.) But, it should be ob- 

 served, that the compression of the marl by its own weight, as 

 thrown into the cart, and still more by the settling during the tra- 

 vel to the field, permits and causes more bushels of marl (if pre- 

 viously measured) to be put into the body than would be indicated 

 by its cubic capacity. Thus, into the cart described above, at an- 

 other time, the marl was put in at the pit by a half-bushel measure, 

 heaped as usual and which heaping certainly added as much as 

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