334 THE POTATO AND ITS COMMERCIAL PRODUCTS. 



America, unless in an atmosphere where the thermometer does not sink, 

 below 40°. If it falls below that, they chill and rot ; and if the temperature 

 rises above 60°, they will grow. 



The extension of potato cultivation has been particularly rapid during 

 the present century, not only in Great Britain and Ireland, but in Europe 

 and North America. Potatoes are now very largely grown in France, 

 Italy, and Germauy ; and, with the exception of the Irish, the Swiss have 

 become their greatest consumers. They were introduced into India at the 

 close of the last century, and are now successfully cidtivated in Bengal and 

 Madras, Java, the Philippines, and China. But the potato does not thrive 

 within the tropics, unless it be raised at an elevation of 3,000 or 4,000 

 feet above the level of the sea ; so that it can never come into very general 

 use in those regions. The Swiss early grew potatoes among their moun- 

 tains, and had learnt the art of drying and grinding them into flour, and 

 making them into bread. A traveller, in 1730, relates that the miller of 

 Untersen had scarcely anything to grind but potatoes. 



The New Zealander owes his potatoes to England, and his koo-mur-ra, 

 or sweet potato, probably also to other foreigners ; although, as Capt. Cook 

 noticed plantations of the latter, they may have been indigenous. Potatoes 

 are not so much used for food in the United States as in Europe ; yet the 

 crops raised over the whole country appear to be very great, probably 

 150,000,000 bushels yearly. The crop there varies from 50 to 250 bushels 

 per acre. 



So rapid an extension of the taste for and the cultivation of an 

 exotic has no parallel in the history of industry ; it has had, and will con- 

 tinue to have, the most powerful influence on the condition of mankind. 

 It can be cultivated on a small as well as a large scale, is under every 

 system of agriculture a beneficial object, and produces more nutriment, 

 upon the same extent of ground, than any other plant cultivated in the 

 temperate regions. It may thus be regarded as the plantain of the tem- 

 perate zone. The potato now forms a great part of the food of the inhabit- 

 ants of Europe, and its introduction as a supplementary crop has greatly 

 lessened the hazards of famine. 



It would not be very far wrong to estimate the consumption of potatoes 

 in the Metropolis at lib. for each adult per day, which, for an adult 

 population of 2,000,000, would give 326,000 tons used up in London 

 yearly. There are about two millions and a half of acres under culture with 

 potatoes in the United Kingdom. If these averaged as much as 5 tons to 

 the acre, this would give 12,500,000 tons of potatoes as the entire annual 

 produce. Taking the value at 31. per ton, this would amount to 37,500,000Z. ; 

 rather a large item, it must be admitted, for one root-crop. In October 1860, 

 a Mr Wallace, of North Berwick Mains, sold all the potatoes on his farm 

 (73 Scotch acres) at the high price of 57Z. 10s. per acre ; so that he realised 

 4,197/. for his potato crop alone. 



The comparative yield of potatoes, of course, depends much on soil, 

 season, care in cultivation, and other points. Mr Knight, when President 



