must be impoffible. The increase of these is in an inverse proportion to that of the Nile; and when the river begins to overflow, the lakes diminish, fo as to appear only like little ponds, when the river has attained it's greateft height: on the contrary, the water appears to return into them as the height of the Nile decreases, and they inundate a long tract of the valley, when the river is at it's ebb.

Struck with this regular difference between the periods at which the waters of the Nile, and those of the lakes of natron, rife and fall, the Egyptians. imagine, that the river acts on the body of water in the defert; as if this action, fuppofing it to exist, would not have produced an opposite effect to that which takes place; whereas in this cafe it is obvious, that the overflow of the Nile and the lakes, as well as their decrease, must have taken place nearly at the fame time. But if we confider, that the augmentation of the Nile, occafioned by the rains in Abyffinia, commences at the fummer folftice, the very time when the weather is hottest and drieft; and juft as the river decreases, or during the winter, the rains never fail to be copious in the northern part of this country; we shall be aware, that the feafon when the Nile increases must be that in which the water fpread over the fand diminishes and dries up, and that local rains, which can have no influence on the overflow of the Nile,

are

are fufficient to render the springs, that furnish this collection of water, more abundant.

When the two lakes feparate, and their waters retire, the foil they had inundated, and which they have now left uncovered, is loaded with a sediment, crystalized and hardened by the fun. This is the natron. The thickness of this layer of falt varies according as the water has remained a longer or fhorter period on the ground. In places where it has merely wetted it for a very fhort time the natron exhibits only a flight efflorefcence, resembling flakes of fnow. I have been told, that at certain periods this fubftance covers the furface of the water. Granger fays, in his account of his Travels in Egypt, that at the end of Auguft the falt of the lake was concreted on the furface, and thick enough for camels to pafs over it; but when I faw it, it was clear and limpid. It is perhaps the most diuretic of all waters; a property for which it is indebted to the faline particles it contains: and the physician, whofe art ceafes to be conjectural only when it is guided by natural philofophy, will perhaps find in it's ufe fimple and natural means of curing obftructions and infarctions of the vifcera, as well as fome other difeafes, that are pretty common in Egypt.

must be impoffible. The increase of these is in an inverse proportion to that of the Nile; and when the river begins to overflow, the lakes diminish, so as to appear only like little ponds, when the river has attained it's greatest height: on the contrary, the water appears to return into them as the height of the Nile decreafes, and they inundate a long tract of the valley, when the river is at it's ebb.

: Struck with this regular difference between the periods at which the waters of the Nile, and those of the lakes of natron, rife and fall, the Egyptians imagine, that the river acts on the body of water in the defert; as if this action, fuppofing it to exift, would not have produced an opposite effect to that which takes place; whereas in this cafe it is obvious, that the overflow of the Nile and the lakes, as well as their decrease, must have taken place nearly at the fame time. But if we confider, that the augmentation of the Nile, occafioned by the rains in Abyffinia, commences at the fummer folftice, the very time when the weather is hotteft and drieft; and just as the river decreases, or during the winter, the rains never fail to be copious in the northern part of this country; we shall be aware, that the feafon when the Nile increases must be that in which the water fpread over the fand diminishes and dries up, and that local rains, which can have no influence on the overflow of the Nile,

are

*

are fufficient to render the springs, that furnifh this collection of water, more abundant.

When the two lakes feparate, and their waters retire, the foil they had inundated, and which they have now left uncovered, is loaded with a fediment, cryftalized and hardened by the fun. This is the natron. The thickness of this layer of falt varies according as the water has remained a longer or shorter period on the ground. In places where it has merely wetted it for a very fhort time the natron exhibits only a flight efflorefcence, resembling flakes of fnow. I have been told, that at certain periods this fubftance covers the furface of the water. Granger fays, in his account of his Travels in Egypt, that at the end of Auguft the falt of the lake was concreted on the furface, and thick enough for camels to pafs over it; but when I faw it, it was clear and limpid. It is perhaps the most diuretic of all waters; a property for which it is indebted to the faline particles it contains: and the physician, whose art ceases to be conjectural only when it is guided by natural philofophy, will perhaps find in it's ufe fimple and natural means of curing obftructions and infarctions of the vifcera, as well as fome other difeafes, that are pretty common in Egypt.

This natron is procured chiefly in the month of Auguft. It is found also, though in lefs quantity, during all the reft of the year. It is feparated from the ground with iron inftruments, and carried on the backs of camels to Terrana, where it is fhipped on the Nile, to be conveyed to Cairo, or to the warehouses at Rofetta. Here twelve hundred and fifty tuns are collected annually, and much more might be obtained. It's common price, delivered either at Cairo or Rofetta, is fifteen or eighteen medins a hundred weight.

Before you reach the lakes, there is a fmall house on the declivity of the hill, in which the Cophts fay a faint was born, to whom they pay particular honour. They call him Maximous; probably the Saint Maximus, or Saint Maximinus, of the catholic legends.

I ftaid fome time near the lakes, the borders of which I traversed: at length we refumed our journey, continuing our courfe to the fouth-weft. The fand, over which we travelled, was completely covered with hardened natron, which rendered our progrefs toilfome and fatiguing both to us and our beafts. We arrived within a fhort diftance of a large square edifice, in which a few Cophtic monks live fhut up from the world. I do not think, that

there