SAU 
is a thing as certain as it is wonderful. He 
had contrived for his own use a commo- 
dious notation for any large numbers, which 
he could express on liis abacus, or calculat- 
ing table, and with which he could readily 
perform any arithmetical operations, by the 
sense of feeling only, for which reason it 
was called his Palpable Aritlimetic. 
His calculating table was a smooth thin 
board, a little more than a foot square, 
raised upon a small frame, so as to lie hol- 
low, which board was divided into a great 
number of little squares, by lines intersect- 
ing one another perpendicularly, and paral- 
lel to the sides of the table, and the parallel 
ones only one-tenth of an inch from 'each 
other ; so that eveiy square inch of the table 
was thus divided into 100 little squares. At 
every point of intersection the board was 
perforated by small holes, capable of re- 
ceiving a pin ; for it was by the help of pins 
stuck up to the head through these holes, 
that he expressed his numbers. He used 
two sorts of pins, a large and a smaller sort ; 
at least their heads were diiferent, and 
might easily be distinguished by feeling. 
Of these pins he had a large quantity in 
two boxes, with their points cut off, which 
always stood ready before him when he 
calculated. The writer of that account de- 
scribes particularly the whole process of 
using the machine, and concludes ; “ He 
could place and displace his pins with in- 
credible niinbleness and facility, much to 
the pleasure and surprise of all the be- 
holders. He could even break off in the 
middle of a calculation, and resume it when 
he pleased, and could presently know the 
condition of it, by only drawing his fingers 
gently over the table.” 
SAURURUS, in botany, a genus of the 
Heptandria Trigynia class and order. Na- 
tural order of Piperitae. Naiades, Jussieu. 
Essential eharacter : calyx an ament with 
one-flowered scales ; corolla none ; germs 
four ; berries four, one seeded. There is 
but one species; viz. S. cernuus, lizard’s tail, 
a native of North America. 
SAUVAGESIA, in botany, so named in 
honour of Francois Boissier de Sauvages, 
professor at Montpellier, a genus of the 
Pentandria Monogynia class and order. 
Natural order of Gruinales. Essential cha- 
racter: calyx five-leaved; corolla five- 
petalled, fringed; nectary five-leaved, alter- 
nate with the petals; capsule one-celled. 
There is but one species; viz. S. erecta, a 
native of St. Domingo, Martinico, Jamaica, 
Surinam, and Guiana. 
SAW 
_ SAW, an instrument which serves to cut 
into pieces several solid matters, as wood, 
stone, ivory, &c. The best saws are. of 
tempered steel ground bright and smooth: 
those of iron are only hammer-hardened : 
hence, the first, besides their being stiflfer, 
are likewise found smoother than the last. 
They are known to be well hammered by 
the stiff bending of the blade ; and to be 
well and evenly ground, by their bending 
equally in a bow. The edge in which are 
the teeth is always thicker than the back, 
because the back is to follow the edge. The 
teeth are cut and sharpened with a triangu- 
lar file, the blade of the saw being first fixed 
in a whetting block. After they have been 
filed the teeth are set, that is, turned out of 
the right line, that they may make the fis- 
sure the wider, that the back may follow 
the better. The teeth are always set ranker 
for coarse cheap stuff than for hard and 
fine, because the ranker the teeth are set 
the more stuff is lost in the kerf. The saws 
by which marble and other stones are cut 
have no teeth: these are generally very 
large, and are stretched out and held even 
by a frame. The workmen who make the 
greatest use of the saw, are the sawyers, 
carpenters, joiners, cabinet-makers, ebo’ 
nists, stone-cutters, carvers, sculptors, &c. 
The lapidaries too have their saw, as well ag 
the workers in mosaic ; but these bear little 
resemblance to the common saw. But of 
all mechanics, none have so many saws as 
the joiners; the chief are as follows : the pit 
saw, which is a large two-handed saw, used 
to saw timber in pits; this is chiefly used 
by the sawyers. The whip-saw, which is also 
two-handed, used in sawing such large pieces 
of stuff as the hand-saw will not easily reach. 
The hand-saw, which is made for a single 
man’s use, of which there are various kinds; 
as the bow or frame saw, which is furnished 
w'ith cheeks : by the twisted cords which 
pass from the upper parts of these cheeks, 
and tire tongue in the middle of them, the 
upper ends are drawn closer together, and 
the low’er set further apart. The tenon-saw, 
which being very thin, has a back to keep 
it from bending. The compass-saw, which 
is very small, and its teeth usually not set : 
its use is to cut a round, or any other com- 
pass-kerf: hence the edge is made broad 
and the back thin, that it may have a com- 
pass to turn in. 
The surgeons also use a saw to cut off 
bones ; this should be very small and light, in 
order to be managed with the greater ease 
and freedom, the blade exceedingly fine, 
