When the tree grows old, the branches wither, and, in place of milk, the inside appears to be full of powder, which is so pungent, that the small dust which I drew upon striking a withered branch seemed to threaten to make me sneeze to death, and the touching of the milk with my fingers excoriated them as if scalded with boiling water; yet I everywhere observed the wood-pecker piercing the rotten branches with its beak, and eating the insects, without any impression upon its olfactory nerves. The only use the Abyssinians make of this is for tanning hides, at least for taking off the first hair. As we went west, the tree turned poor, the branches were few, seldom above two or three ribs, or divisions, and these not deeply indented, whereas those of Taranta had frequently eight. We afterwards saw some of them at the source of the Nile, in the cliff where the village of Geesh is situated, but, though upon very good ground, they did not seem to thrive; on the contrary, where they grew on Taranta it was sandy, stony, poor earth, scarce deep enough to cover the rock, but I suspect they received some benefit from their vicinity to the sea. Some botanists who have seen the drawing have supposed this to be the euphorbia officinarum of Linnæus; but, without pretending to great skill in this matter, I should fear there would be some objection to this supposition: First, on account of the flower, which is certainly rosaceous, composed of several petals, and is not campaniform: Secondly, That it produces no sort of gum, either spontaneously or upon incision, at no period of its growth; therefore I imagine that the gum which comes from Africa in small pieces, first white on its arrival, then turning yellow by age, is not the produce of this tree, which, it may be depended upon, produces no gum whatever. Juba the younger is said, by Pliny, to have given this name to the plant, calling it after his own physician, brother to Musa physician to Augustus. We need not trouble ourselves with what Juba says of it, he is a worse naturalist and worse historian than the Nubian geographer. RACK. This is a large tree, and seems peculiar to warm climates. It abounds in Arabia Felix, in Abyssinia, that is, in the low part of it, and in Nubia. The first place I saw it in was in Raback, a port in the Red Sea, where I discovered this singularity, that it grew in the sea within low-water mark. When we arrived at Masuah, in making a plan of the harbour, I saw a number of these in two islands both uninhabited, and without water, the one called Shekh Seide, the other Toulahout. These two islands are constantly overflowed by salt water, and though they are strangers to fresh, they yet produce large Rack-trees, which appear in a flourishing state, as if planted in a situation designed for them by nature. [Illustration: _Rack_ _London Publish’d Dec.^r 1.^{st} 1789 by G. Robinson & Co._]