ed rim of the Spanish Arabic Turkomanic shoe is observed to be
undergoing a change to that of a groove. The broad surface of the shoe
evidently led to the beveling of the same, so as to lessen sole
pressure. The size of the nail holes remains still like that of the
Huns; but the unsunk southern nail heads yet serve to improve the hold
on the ground. The calks were next placed forward, perhaps from an
uncultivated sense of beauty, or from the high bending up of the hind
part of the shoe, which would necessitate a high and heavy unsightly
calk.

From this time on horseshoeing in south Germany fell back very
quickly, and loses all scientific holds of support after the thirty
years war. In the mean time toe protection in the form of a calk had
spread from the colder north over southern Germany; whereas this north
German invention did not find favor in England in consequence of her
mild oceanic climate.

[Illustration: FIG. 22]

Also, the calks in England, as well as in the southern countries, on
the same ground, therefore, with good reason, could at no time be
adopted. This did, however, not interfere with the use of the calk in
the colder south Germany, where after a use of nearly 1,500 years it
has maintained its local and climatic adaptation. Notwithstanding the
occasional aping by foreigners, it has remained victorious in its
original form, and has been chosen in many countries.

The historical development of the horseshoe in general, from about the
time of Emperor Maximilian until the seven years war, furnishes a true
picture of the confused condition of things at that period of time,
which, to make intelligible, would require a separate and complete
treatise. Interesting as it is to the scientist to follow up this
development and mode of present German horseshoeing, which, aside from
the national toe and calk, is the English form and has become
influential, and with full right, for a periodical of this kind
further, more comprehensive, statement would under all circumstances
take up too much room; therefore I must drop the pen, although
reluctantly.

[Illustration: FIG. 23.]

* * * * *

SHEET GLASS FROM MOLTEN METAL.

The present practice in making metal sheets is to cast ingots or slabs
and then reduce these by repeated rollings and reheating. Attempts
have been previously made to produce sheets directly from molten metal
by pouring the metal: (1) between two revolvin