Thus the fame of Arabian olibanum was dying away, and so was our knowledge of that and the opposite African coast, when Colebrooke (1807) published his Essay on Olibanum, in which he showed that a gum-resin, identical as he considered with frankincense, and so named (Kundur), was used in India, and was the produce of an indigenous tree, Boswellia serrata of Roxburgh, but thereafter known as B. thurifera.  This discovery, connecting itself, it may be supposed, with Niebuhr’s statements about Indian olibanum (though probably misunderstood), and with the older tradition coming down from Dioscorides of a so-called Indian libanos (supra p. 396), seems to have induced a hasty and general assumption that the Indian resin was the olibanum of commerce; insomuch that the very existence of Arabian olibanum came to be treated as a matter of doubt in some respectable books, and that down to a very recent date.

In the Atlas to Bruce’s Travels is figured a plant under the name of Angoua, which the Abyssinians believed to produce true olibanum, and which Bruce says did really produce a gum resembling it.

In 1837 Lieut.  Cruttenden of the Indian Navy saw the frankincense tree of Arabia on a journey inland from Merbat, and during the ensuing year the trees of the Sumali country were seen, and partially described by Kempthorne, and Vaughan of the same service, and by Cruttenden himself.  Captain Haines also in his report of the Survey of the Hadhramaut coast in 1843-1844[2] speaks, apparently as an eyewitness, of the frankincense trees about Dhafar as extremely numerous, and adds that from 3000 to 10,000 maunds were annually exported “from Merbat and Dhafar.” “3 to 10” is vague enough; but as the kind of maund is not specified it is vaguer still.  Maunds differ as much as livres Francais and livres sterling.  In 1844 and 1846 Dr. Carter also had opportunities of examining olibanum trees on this coast, which he turned to good account, sending to Government cuttings, specimens, and drawings, and publishing a paper on the subject in the Journal of the Bombay Branch of the R. As.  Society (1847).

[Illustration:  The Harvest of Frankincense in Arabia.  Facsimile of an engraving in Thevet’s Cosmographie Universelle (1575), reproduced from the Bible Educator.[3]]

But neither Dr. Carter’s paper and specimens, nor the previous looser notices of the naval officers, seemed to attract any attention, and men of no small repute went on repeating in their manuals the old story about Indian olibanum.  Dr. G. Birdwood however, at Bombay, in the years following 1859, took up the subject with great zeal and intelligence, procuring numerous specimens of the Sumali trees and products; and his monograph of the genus Boswellia in the Linnaean Transactions (read April 1869), to which this note is very greatly indebted, is a most interesting paper, and may be looked on, I believe, as embodying the most correct knowledge as yet attainable.  The species as ranked in his table are the following: