HARDWICKE'S S UIENCE- GO SSIP. 



223 



&c. Thus it may be truly said that nearly every 

 country of the world has one or more representatives 

 flourishing here, and that they here flower annually, 

 and ripen their seed. The Mesembryanthemuins, 

 Sedums, Echeveiias present glorious masses of 

 flower, or of strange un-English foliage. But to 

 the casual visitor, perhaps the Agaves, of which 

 there are this year (1875) 4S coming into blossom, 

 with stems of 20 or 30 ft. high, are the most striking 

 of all the plants." 



I cannot print the entire list given to be me by 

 Mr. Gardiner, but have probably quoted enough to 

 show how marvellous is the grasp of the climate, if 

 only protection from the wind be given. Then how 

 strange is it to find that no stone-fruit (not even 

 the Plum or Cherry) will ripen in the islands, 

 though the trees blossom freely, and of frost there 

 is none to cut off the bloom. And, further, no 

 indigenous wild plant grows here with more vigour 

 (so far as I could see or learn) than it exhibits on 

 the mainland of England. The home-grown apples 

 are much praised by the Scillonians, but I doubt if 

 a Covent-garden dealer would value highly the 

 small fruit, which hangs in crowded clusters on the 

 trees grey with lichen. The Blackberry blossoms 

 abundantly, but I learn that the berry is in flavour 

 far below that which is yielded by the hedges of 

 Kent or Surrey. The Eurze, Bracken-fern, Tree- 

 mallow, Foxglove, &c, are not more luxuriant, even 

 when best sheltered from the wind, than we see 

 them about London. It may be well to inquire 

 why a climate which is so genial as to suit the Ara- 

 lias, Dracaenas, Palms, and Bananas, should be 

 totally unsuited to even the hardiest stone-fruit, and 

 should add nothing to the growth of the common 

 English plants. 



Through the kindness of Mr. Thomas, who has 

 charge of the Meteorological observations in St. 

 Mary's, I obtained copies of the Weather records 

 for the years 1872-3-4, and place some of the 

 observed facts in comparison with corresponding 



facts for Guernsey and Greenwich, in the preceding 

 table, which shows the mean (for 1872-3-4) of the 

 highest and lowest temperatures observed in^the 

 three places respectively. 



We can from this table find the explanation of the 

 freedom of growth given to some forms of vege- 

 tation, combined with the restrictions imposed on 

 the development of other forms ; for although the 

 climate of Scilly is moist (37 inches being about the 

 annual rain-fall, as compared with 24 for London) 

 and the prevalence of foggy or cloudy weather is 

 greater than at Greenwich, yet as the rain-fall 

 during the summer months is not greater than that 

 at Greenwich, and the proportion of direct sun-light 

 is probably, during the same months, but little below 

 that at Greenwich, neither of these two character- 

 istics can account entirely for the failure of stone- 

 fruit. 



We observe then that at Greenwich there are 

 only four or five months within which frost may not 

 probably occur. In Scilly frosts occur but seldom, 

 and then last usually only for a few hours. Hence 

 a large class of plants which could not live without 

 shelter at Greenwich during more than about four 

 months in the year, can live permanently out of 

 doors in Scilly. But as the summer in Scilly is 

 not hotter than May in London, fruits which for 

 ripening require a heat above that of late spring, 

 find the island-climate unsuited to them. Obviously 

 the English plants in Scilly which are at rest during 

 winter get little or no advantage from the mild 

 temperature at that season, while they are less 

 stimulated to growth (during the cool summer) than 

 they would have been in the neighbourhood of 

 London. 



I had not expected that a removal of only about 

 thirty miles from the mainland, with but a small 

 gain in latitude, as compared with the coasts of 

 Devon and Dorset, could have produced so great an 

 effect on vegetation as I here saw. 



While looking at the foreign character of the 

 foliage in the Tresco gardens, one is led to consider 

 how far the facts there put before us serve to ex- 

 plain the remains of sub-tropical plants, which, 

 geologists show us, occur plentifully in the clays 

 and shales of countries where now a cold climate 

 prevails. We learn from Scilly that if only the 

 cold of our English winter be moderated, our sum- 

 mer is sufficiently warm for the vigorous growth of 

 many plants indigenous to Australia, New Zealand, 

 China, the Cape of Good Hope, &c. ; and further, 

 that this moderation of the winter cold can be 

 effected by only a change in the extent of land 

 surface compared with the extent of water surface. 

 Before assuming a necessity for such gigantic 

 variations as the shifting of our earth's axis, it is 

 good to see how much a simple extension of water 

 surface will account for as regards climate. 

 On glancing over the table, it will be seen that 



