TRACTS ON VARIOUS SUBJECTS, &c. 28 



and would maintain the potatoe grounds in good heart. These 

 might, no doubt, be further improved by rotations of corn and 

 green crops, which would prevent those disappointments that 

 arise after perpetual croppings of potatoes for 12 or 14 years 

 without manure. By such a practice, labour becomes useless, its 

 expenses are thrown away; and the lands, originally productive, 

 are, in the end, completely exhausted. This is a fact well known 

 to the planters. 



It has already been mentioned that the greatest produce was 

 from experiment No. 5 ; which was large seed cut in pieces, 

 planted 12 inches deep, and manured with horse dung litter. 

 Thirty feet of the rows yielded 50 pounds of very fine potatoes, 

 which is at the rate of 648 bushels per acre. 



To those who are unaccustomed to such calculations, it may 

 be proper to explain in what manner the results in the Table are 

 computed, from the length of 30 feet of rows. 



An English statute acre consists of 10 square chains. This may 

 be more readily comprehended by imagining a space one chain 

 in brendth, and ten in length. As a chain measures 66 feet, it is 

 evident an acre of the above form will be 66 feet broad, and 660 

 feet long — and consequently the contents of an acre are 43560 

 square feet. 



If this acre be planted in rows, 2 feet asunder, there may be 

 placed 33 rows in its breadth — and this number of rows, multi- 

 plied by 660 feet, will give 21780 feet for the total length of the 

 rows. Then, if this sum be divj<led by 30 feet, it will be found 

 that this length of rows is exactly the 726th part of an acre — con- 

 sequently, the produce, in pounds, of any one of my experiments, 

 multiplied by 726, wdl give the acreable produce in pounds. To 

 find this produce in bushels, divide by 56 pounds, the weight of 

 a St. Helena bushel. 



