and the Means of ascertaining it. 337 



Henry Ranjovius, planted a certain number of trees in 1580, in 

 Ditmarsen, of various kinds, and placed stones near them, on 

 which he engraved their dates, that posterity, as he said, might 

 be aware of theii- age. It would be curious to know whether 

 these trees are still in existence, and, in such a case, tp get their 

 circumference. It is a question that I address to Danes who 

 are fond of science, and, in general, it would be curious to 

 have the circumference of every tree whose date is known, and 

 is upwards of a century old. I would even venture to invite 

 all those who have similar documents, either to publish them, 

 or communicate them to me, as these facts are very useful by 

 their comparison with others. 



3. As to trees 100 years old, it is useful to get their circum- 

 ference at various known periods, in order to compare them with 

 each other, or with other raeasureinents of the same tree, which 

 may have been made at an earlier or a later period. These compa- 

 risons would afford means for a more accurate calculation of the 

 law of the growth, and appreciating the influence of the difference 

 of age. Thus the cedar, in the Jardin de Paris, for example, 

 measured when eighty-three years old, was 106 inches in cir- 

 cumference, which would indicate a mean increase of five lines 

 annually ; but it had been measured at the age of forty years, 

 and at that time was above 79 inches round. We are thus aware 

 that, during the first forty years, it increased 7^ lines annually, 

 and only 2J for the succeeding forty-three ; consequently, if we 

 were going to calculate the age of a very old cedar, we should 

 not be very far wrong did we take the latter as the multiplier. 

 Thus the cedars measured at Lebanon in 1660 by Maundrel and 

 Pococke, which were 12 yards and 6 inches round, English mea- 

 sure (it may be about 1527 lines in diameter royal measure), 

 should be about 609 y^ars old, and nearly 800 in 1787, when 

 they were revisited by Mr Labillardiere. This calculation is 

 doubtful, however, as it is founded on a single example ; it 

 would be much more certain were the number of examples in- 

 creased. 



4. It would also be useful to take the circumference of some 

 very old trees which we may meet, even though we are igno- 

 rant of the time when they were planted. Such measurements 

 repeated at stated intervals, would inform us of the law of the 



'i^i.. XV. NO. XXX. OCTOBKR 1833. Y 



