in such cases; where their impression is found, as not unfrequently happens, on bricks of this kind, the brick has been laid upon reed matting when in a soft state, and afterwards submitted to the action of fire.  In edifices of crude brick, the reeds were no doubt of great service, and have enabled some buildings of the kind to endure to the present day.  They are very strikingly conspicuous where they occur, since they stripe the whole building with continuous horizontal lines, having at a distance somewhat the effect of the courses of dark marble in an Italian structure of the Byzantine period.

Another characteristic of the edifices in which crude brick is thus largely employed, is the addition externally of solid and massive buttresses of the burnt material.  These buttresses have sometimes a very considerable projection; they are broad, but not high, extending less than half way up the walls against which they are placed.

Two kinds of cement are used in the early structures.  One is a coarse clay or mud, which is sometimes mixed with chopped straw; the other is bitumen.  This last is of an excellent quality, and the bricks which it unites adhere often so firmly together that they can with difficulty be separated.  As a gen eral rule, in the early buildings, the crude brick is laid in mud, while the bitumen is used to cement together the burnt bricks.

[Illustration:  PLATE 8]

These general remarks will receive their best illustration from a detailed description of the principal early edifices which recent researches in Lower Mesopotamia have revealed to us.  These are for the most part temples; but in one or two cases the edifice explored is thought to have been a residence, so that the domestic architecture of the period may be regarded as known to us, at least in some degree.  The temples most carefully examined hitherto are those at Warka, Mugheir, and Abu-Shahrein, the first of which was explored by Mr. Loftus in 1854, the second by Mr. Taylor in the same year, and the third by the same traveller in 1855.  The Warka ruin is called by the natives Bowariyeh, which signifies “reed mats,” in allusion to a peculiarity, already noticed, in its construction. [PLATE VIII., Fig. 1.] It is at once the most central and the loftiest ruin in the place.  At first sight it appears to have been a cone or pyramid; but further examination proves that it was in reality a tower, 200 feet square at the base, built in two stories, the lower story being composed entirely of sun-dried bricks laid in mud, and protected at intervals of four or five feet by layers of reeds, while the upper one was composed of the same material, faced with burnt brick.  Of the upper stage very little remains; and this little is of a later date than the inferior story, which bears marks of a very high antiquity.  The sundried bricks whereof the lower story is composed are “rudely moulded of very incoherent earth, mixed with fragments