82 



THE TROPICAL AGRICULTURIST. 



[July i, 1882. 



six tiiiics as great as it is in the country (Lieb- 

 fraupn))era), a result no doubt due to the ammonia 

 evolved ilunng the combustion of fuel and to nnimal 

 exhalations; and to the same cause may be attributed 

 the excessive quantity of nitrogen found in the fogs 

 of Paris. We also observe tliat dew is richer in 

 plant-food than rain, which may serve to some extent to 

 explain its rt-markablv irivigor.ating efT'iet on vegetation. 

 Again, Lavves, Gdbi-rt, and Warington have lately 

 published m the Journal of the Royal Agrkullural 

 Soc'cfii* the following analyses of rain, dew, and 

 hoar-trost collected at Rothamsted, and determined 

 by Dr. Frankland. 



Table II. — Showing ike Maximum, Minimum, and Mean 

 Amounts of Certain Constituents in Sixty-nine Samples 

 of Rain-water, collected at Itothamsted, in parts pr 

 million .^ 



Table III. — Showing the Maximum, Minimum, and Mean 

 Amounts of Certain Constitueiits of in Sevin Samples of 

 Dew and Hoar Frost, Collected at Rothamsted, in parts 

 per million. 



Ii) the analyses by Boussingault of aqueous deposits 

 collected at Ijiebfrauenberg we find that dews are 

 twice ae rich in nitrogenous compounds .as rain-w.iter, 

 while at Rothamfted, from .analj'ses made by Dr. 

 Fraaliland hy improved methods, nearly twenty years 

 later, we find that these sm.all deposits condensed 

 from -the lower slr.ituni of the atmosphere contain 

 oil an average thiee or four times the amount of 

 ori^an'C carbon, organic nitmgen, ammonia, and nilrio 

 acid found in the analy.-cs of rain-water. The total 

 quantity of solid matter and the amount of chlorides 

 is also larger, but the dilTerenec is mueli smaller 

 than in the case of the other ingredient--. 



It mny be a*ked why sn^w and linar-frost should 

 be white? The question is a natural one, but the 

 answer is easily given. If snow hail been black it 

 would have rap'ully absorbed Un' sun's rays and 

 been thawed by the first sunshine which fell upon 

 it, the result of which wonhl have been that veget- 

 ation, being prematurely deprived of that proteciiou 

 which Nature intended to guird it agdust the cold, 

 would have died in the frosty air as soon as the 

 sun had set. But the heat-reliecting and uou-con- 

 duoting "white snow" and "hoar-frost" .are of the 

 utmost importance as a protectioa against sudden 



*'Vol. xviii. ,ss. , parti, f Mean of thirty. four analyses. 

 X Mean of four analyses. 



alterations of heat or cold, for while it is melting 

 its temperature never varies from .32° Fahr., and the 

 plants which are enveloped in it rarely suffer a much 

 lower, and cannot be exposed to a hi, ;her temperature. 

 Hence we observe that frosts in spring i i- in early 

 autumn generally do more damage to vegetation than 

 the prolonged frost and excessive cold of winter, 

 because the sun's rays act quickly upon the unpro- 

 tected frozen plants, ami by a sudden alteration in 

 their warmth induce a change inconsistent with their 

 vitality. Therefore gardeners duriug the winter season 

 should take as much care to protect tlieir plants 

 from the sun's heat as from the frost's cold.— F. F. 

 W; Harpenden, February, 19,S2.— Gardeners' Chronicle. 



TRAVELS OF PLANTS. 



The wild plants of Peru and Chili were carried by 

 the first explorers of those countries to Spain long 

 before they grew in England or Ireland. Potatos were 

 in Burgundy in 15G0, and in Italy about the same 

 time. In 1584 they were at Yousjhal, but it was 

 not until thirty years later that they took firm hold 

 of the ground in Ireland on their re-introduction at 

 Youghal by Sir Walter Ptaleigh. Meanwhile Gerard, 

 the herbalist, received from Sir Francis Drake some 

 tubt-rs, which he planted in his garden at Holborn. 

 In 1663 the F.oyal Society published rules for the 

 cultivation of the new crop. The Dutch carried the 

 Potato to the Cape, aii'l it passed into India in 1800, 

 and has generally spread over the whole world, being 

 confined in hot countries to the hills. The' Potato 

 recalls the memories of an age of travels and voyages, 

 when Drake sailed westwards with his five ships, 

 singeing the King of Spain's beard on his passage, 

 and re. appearing to be dubbed Sir Francis after 

 having circumnavigated the globe. The nation was 

 at all tiuies extremely curious as to foreign countries, 

 and having become wealthy by means of trade and 

 the growth of wool, it naturally welcomed travelled 

 plants and introduced them in its gardens. In ex- 

 change for the Potato and two other plants, Tobacco 

 and Cinchona, America obtained from this hemisphere 

 Sugar, Coffee, and the Coconut. 



A woid or two on the Sugar-cane, a plant allied 

 'to the Indian Piattan, but in the estimation of schoolboys 

 widely ciiSerent in flavour — the one being bitter, 

 and the other sweet. We pass over its early travels 

 from its home in China, and notice only its passage 

 into Spain with the Moors, into M-uleira and Mexico 

 with the Spaniards, into Brazil with the Portuguese, 

 into Barbadoes and Jamaica with the English colonists 

 in the seventeenth century, and into Bourbon and 

 Mauritius with the French. 



The exchange of plants between America and the 

 Old World includes Wheat and Maize, whose typical 

 climate? are widely difierent. It is the habit of Alaize 

 to commence its growth suddenly at a gallop in Jnue. 

 Wheat, on the contrary, prefers to advam-e gradunlly, 

 and it breaks down with rust and mildew when forced 

 on by an excess of sun, without a sulBeieut pause 

 between seed time and harvest. Maize has been known 

 to run its course in ninety days, and to reach the 

 threshing floor to the tune of IGO bushels per acre. 

 It is not surprising, therefore, that this prolific grain 

 should have accompanied the colonists of various 

 nations "ver the whole of America from Chili to 

 the cluaiu of lakes. It was introduced into g.ardens 

 on this side of the Atlantic within fifty years of tha 

 first voyage of Columbus. It entered the Mediterranean 

 by waj' of Spiin, and before the death of Queen 

 Elizabeth and her counsellors — two of whom were 

 noted gardeners. It reached the Levant, where it 

 became an important item in the trade of the Venetians. 

 It afterwards passed up the Danube to Hungary, 

 and travelling eastward with the merchandise o 



