JSfATURAL HISTORY. ' 519 



eonditiona. But -wliat constitutes exactly similar conditions in an enquiry like 

 this ? Exactitude, literally speaking, can never enter into such enquiries. No two 

 trees ever existed under circumstances exactly similar. All that can be required 

 is that conditions shall be tolei-ably similar, which was far from being the case 

 with Zuccarini's specimens of Yews, obtained, as he tells us, from situations on 

 the Bavarian Alps differing by 3000 feet of elevation above the sea. 



Sufficiently similar conditions would, we think, in a case like this, be found in 

 the comparison of old English Oaks with one another, and on that point we would 

 for the present fix attention. Is there any tolerable uniformity of growth among ■ 

 English Oaks which remain to acquire anything like antiquity ? in other words, 

 among vigorous oaks, for all others would be felled in the ordinary opei-ations of 

 the forester. Perhaps that point is not altogether beyond the reach of inquiry, 

 for many opportunities must occur of measuring the diameter and counting the 

 rings of old oaks when felled ; and there muat also be many standing oaks of some 

 considerable size, the age of which is ascertainable without felling. A collection of 

 such data might be formed from which averages applicable to the inquiry before 

 us might be easily drawn. Unfortunately th-ey can hardly be said to exist at 

 present ; but some are on record, from which, by way of illustration, we have 

 formed the following table. This evidence seems to show that on an average 

 vigorous oaks grow at something like the following rate in England: — 

 In the 1st 50 years they reach 12 inches in diameter [50] 

 " 2nd " "19 " " [100] 



" 8rd " « 26 " " [150] 



" 4th " " 32 " « [200] 



^' 5th " " 86 " " [250] 



" 6th " « 40 " « [300] 



That is to say, a vigorous English oak will, on an average, be rather more than 26 

 inches in diameter when 150 years old, and 40 inches in diameter when 300 years 

 old. In this computation it is assumed that after 100 years the rate of growth is 

 reduced to seven inches for the next 50 years, to six inches for the succeeding 50 

 years, and then falls permanently to an increase of four inches in diameter for 

 tevery half century. 



We find that this mode of recTjoning bripgs the age of the Berkley Oak, 34 feet 

 in circumference, exactly to 1500 years, the period assigned to it by Marsham, 

 and would carry the oak, 47 feet in circumference, mentioned by South, to 2160 

 years. In like manner the great Winfarthing Oak, said to have been called "The 

 ■Old Oak" at the Conquest, and which in 1820 was about 14 feet in diameter, 

 must have been at that time 190O years. 



We have been led into these calculations from a wish to ascertain the age of 

 some superb old Spanish Chesnut trees growing on a terrace overlooking the valley 

 of Sir William Middleton's most beautiful seat at Shrubland Park, near Ipswich. 

 These trees vary in size, but all are venerable objects, twisted like colossal cables, 

 and exemplifying on a gigantic scale the universal fact that the fibrous grain of 

 trees is spiral. Of these one is 44 feet round at the ground, and 27 feet ronnd at 

 -six feet higher up. If the foregoing scale of growth for the Oak is true, and if, as 



