'What remains of this massive erection [the Takht-i-Khosru, or palace of Chosroës Anushirwan, at Ctesiphon] is a mere fragment, which, _to judge from the other extant Sassanian ruins_, cannot have formed so much as one fourth part of the original edifice. Nothing has come down to our day but a single vaulted hall on the grandest scale, together with the mere outer wall of what no doubt constituted the main facade of the building. The apartments, which, _according to all analogy_, must have existed at the two sides, and in the rear, of the great hall, some of which _should_ have been vaulted, have wholly perished. _Imagination may supply_ them from the Firuzabad, or the Mashita palace; but not a trace, even of their foundations, is extant; and the details consequently are uncertain, though the general plan can scarcely be doubted. At each side of the great hall _were probably_ two lateral ones, communicating with each other, and capable of being entered either from the hall or from the outer air. Beyond the great hall _was probably_ a domed chamber equalling it in width, and opening upon a court, round which were a number of moderate-sized apartments. The entire building _was no doubt_ an oblong square, of which the shorter sides seem to have measured 370 feet. It had at least three, and _may not improbably have had_ a larger number of entrances, since it belongs to tranquil times and a secure locality.' *** The most notable argument in the category of concretion is undoubtedly the inference as to the sphericity of the earth. Next is the sub-inference by Columbus that China could be reached by sailing westward from Portugal. If the syllogistic opinion were valid--that a conclusion must be absolutely true or absolutely false--the expedition of Columbus was based on a fallacy. Most people think it was eminently rational. No one has seen the north or the south poles, and the conviction that they could be realised, if certain difficulties of transport were overcome, is a sub-inference of the same character. Here is a common type of inference in perspection-- III. That church | is 100 yards off --------------------+---------------------- A man appears on | _he is_ 100 _ys. off_ the roof of the ch. | And this-- III. That distant house | is 60 ft. high ----------------------------+------------------------ It appears to be scaffolded | _the scaffold is about_ to a third of its height | 20 _feet high_ In these cases we have not seen the man or the scaffolding before, and have not measured the latter or the distance to the former: the conclusions are imaginary judgments fairly drawn from known premises. ***