may be supposed to have done so._[Footnote 2: _There are, in
Algiers, two Monuments, commonly called_ "Le Madracen" _and_ "Le
tombeau de la Chretienne," _which somewhat resemble Leonardo's
design. They are known to have served as the Mausolea of the Kings
of Mauritania. Pomponius Mela, the geographer of the time of the
Emperor Claudius, describes them as having been_ "Monumentum commune
regiae gentis." _See_ Le Madracen, Rapport fait par M. le Grand
Rabbin AB. CAHEN, Constantine 1873--Memoire sur les fouilles
executees au Madras'en .. par le Colonel BRUNON, Constantine
l873.--Deux Mausolees Africains, le Madracen et le tombeau de la
Chretienne par M. J. DE LAURIERE, Tours l874.--Le tombeau de la
Chretienne, Mausolee des rois Mauritaniens par M. BERBRUGGER, Alger
1867.--_I am indebted to M. LE BLANC, of the Institut, and M. LUD,
LALANNE, Bibliothecaire of the Institut for having first pointed out
to me the resemblance between these monuments; while M. ANT. HERON
DE VlLLEFOSSE of the Louvre was kind enough to place the
abovementioned rare works at my disposal. Leonardo's observations on
the coast of Africa are given later in this work. The Herodium near
Bethlehem in Palestine_ (Jebel el Fureidis, _the Frank Mountain)
was, according to the latest researches, constructed on a very
similar plan. See_ Der Frankenberg, von Baurath C. SCHICK in
Jerusalem, Zeitschrift des Deutschen Palastina-Vereins, _Leipzag_
1880, _Vol. III, pages_ 88-99 _and Plates IV and V._ J. P. R.]

_E. Studies for the Central Tower, or Tiburio of Milan Cathedral.

Towards the end of the fifteenth century the Fabbricceria del Duomo
had to settle on the choice of a model for the crowning and central
part of this vast building. We learn from a notice published by G.
L. Calvi [Footnote: G. L. CALVI, Notizie sulla vita e sulle opere