342 
KANSAS CITY REVIEW OF SCIENCE. 
the granite core (Fig. i) the grooves are a double spiral, showing that they were 
made by two stones at opposite sides of the tubes ; the pitch of the thread is y^^ 
inch, the circumference of the core about 7 inches, and therefore the rate of 
sinking was -^-^ of the distance traveled by the tool. The wonder is how any 
bronze tube or saw blade could bear the requisite pressure without doubUng up, 
and how the jewels could be set in sockets to support them against such a violent 
drag. 
Not only was a rotating tool employed, but the further idea of rotating the 
work and fixing the tool was also familiar to the earliest Egyptians. This is evi- 
denced by the fragments of bowls turned in diorite. One piece of the bottom of 
a bowl (Fig. 8) shows the characterized marks of the turning. Not only are 
there the circular grooves of the jewel pointed tool, but also the marks of two 
different centerings, showing that the work had been displaced by the force 
applied in turning, and afterward reset, but not accurately, the old and new sur- 
faces meeting in a cusp. Other specimens of turning in black granite, basalt, 
and alabaster, all of the pyramid period, were exhibited by the author. The 
finest examples of turning in hard stone, however, are in the British Museum, 
Among these are a small, highly-polished, narrow-necked vase in diorite, or 
rather In transparent quartz with horn-blende, which has its neck only 0,05 inch 
thick, and a large vase of syenite turned inside and out remarkably thin consid- 
ering the size of the component crystals. But the greatest triumph is a bowl of 
diorite, translucent and full of minute flaws, which must render it very brittle ; 
yet this bowl, six inches in diameter, is only -^^ of an inch thick (.024) over its 
greatest part; just around the edge it is thicker, but a small piece broken out of 
the body of it shows its extraordinary thiness, no stouter than a thin card. An 
Fig. 8. Fig. 9. 
alabaster vase of Unas of the fifth dynasty, almost rivals this in thinness, being 
only ^ inch to 3^^ inch thick, but the softness of the material makes it of far less 
interest. A very favorite plan for narrow necked vessels was to turn them in 
two or three parts and join these together, sometimes finishing off the inside on a 
fresh centering of the lathe. One example shows that the early Egyptians were 
familiar, not only with jewelled turning tools, but with mechanical tool rests, and 
with sweeping regular arcs in cutting. A fragment of a diorite bowl (Fig. 9) 
shows that the original article was turned as a segment of a sphere inside by a 
