as may have been in use during a journey.  These notes are mostly found in the MSS. books of his later and quieter years, and it is certainly remarkable that Leonardo is very reticent as to the authorities from whom he quotes his facts and observations:  For instance, as to the Straits of Gibraltar, the Nile, the Taurus Mountains and the Tigris and Euphrates.  Is it likely that he, who declared that in all scientific research, his own experience should be the foundation of his statements (see XIX Philosophy No. 987—­991,) should here have made an exception to this rule without mentioning it?

As for instance in the discussion as to the equilibrium of the mass of water in the Mediterranean Sea—­a subject which, it may be observed, had at that time attracted the interest and study of hardly any other observer.  The acute remarks, in Nos. 985—­993, on the presence of shells at the tops of mountains, suffice to prove—­as it seems to me—­that it was not in his nature to allow himself to be betrayed into wide generalisations, extending beyond the limits of his own investigations, even by such brilliant results of personal study.

Most of these Topographical Notes, though suggesting very careful and thorough research, do not however, as has been said, afford necessarily indisputable evidence that that research was Leonardo’s own.  But it must be granted that in more than one instance probability is in favour of this idea.

Among the passages which treat somewhat fully of the topography of Eastern places by far the most interesting is a description of the Taurus Mountains; but as this text is written in the style of a formal report and, in the original, is associated with certain letters which give us the history of its origin, I have thought it best not to sever it from that connection.  It will be found under No.  XXI (Letters).

That Florence, and its neighbourhood, where Leonardo spent his early years, should be nowhere mentioned except in connection with the projects for canals, which occupied his attention for some short time during the first ten years of the XVIth century, need not surprise us.  The various passages relating to the construction of canals in Tuscany, which are put together at the beginning, are immediately followed by those which deal with schemes for canals in Lombardy; and after these come notes on the city and vicinity of Milan as well as on the lakes of North Italy.

The notes on some towns of Central Italy which Leonardo visited in 1502, when in the service of Cesare Borgia, are reproduced here in the same order as in the note book used during these travels (MS. L., Institut de France).  These notes have but little interest in themselves excepting as suggesting his itinerary.  The maps of the districts drawn by Leonardo at the time are more valuable (see No. 1054 note).  The names on these maps are not written from right to left, but in the usual manner, and we are permitted