SCO 
point which forms the letters ; is screwed 
into the bar d; FG is a piece of wood 
glued to the bottom of the box, with a small 
piece of ivory fastened upon the top of it, 
to support the paper while it is written up- 
on : the surface of this ivory is about the 
same height as the brass shelf, a a, as is seen 
in the section fig. 4 : H and I are two small 
rollers, (one of which is shown separately in 
fig. 2) on which the paper is rolled ; it is 
fastened to thejn at both ends, by a small 
brass lever, fc, (fig. 2) which shuts down in 
a groove made in the roller: when the pa- 
per is put under this lever, and shut down, 
it is held fast, and by turning the roll is 
wound upon it : I w are tw'O small milled 
heads, one on each roll, to turn them ; at 
one end of the roll, I, a small rachet wheel, 
t, of six teeth, is fixed ; it is turned round 
by a click, fc, (tig. 4) jointed to a small lever, 
1, which is thrown up by a spring, w. n 
(fig. 1 ) is a piece of brass plate screwed to 
the side of the box : it is shown separately 
in fig. 3, and has two branches, to receive 
the pivots of the two rollers, HI; these 
arms are elastic, and press against the ends 
of the rollers, and causes them to turn rather 
stiffly, so that they will not be liable to be 
moved by the elasticity of the paper which 
is rolled upon them. The pentagraph is of 
the common kind: the three points, gi, 
and the end of A, being all in one line, as 
explained in the article Pentagraph : the 
point i, which forms the letteis, is a short 
piece of silver wire, screwed into the bar d, 
and pointed at the end to make this mark : 
the paper is rubbed over with whiting, or 
chalk ; and when at any time the point is 
worn away, it may be renewed by screwing 
it through the bar a little further: the point 
is always made to project so far, that when 
the blunt point at the end of the pencil, h, 
rests upon the brass shelf, a a, the penta- 
graph will be set a little upon the strain, 
and by that means press upon the paper 
with a proper degree of force to write 
legibly.' In using the machine, the lid, 
F G, is to be half shut, as shown in fig. 5, 
and finis form a support for the hand while 
writing ; the pencil, h, is held in the hand, 
and pressed down to touch the brass shelf, 
a a, and used in the same manner as a com- 
mon pen or pencil, taking care to always 
begin at the end of the shelf; the side of 
the box, and a small ledge upon the edge of 
the shelf, limits the height of the letters. 
When the pencil arrives at the end of the 
shelf, it is to be brought back again, and 
the end of it is to be placed upon the 
SCR 
end of the lever, I, and forced down the 
click, k, then takes into one of the teeth of 
the wheel, t, and turns it round one tooth ; 
the pressure is then to be removed, and the 
spring, m, lifts up the lever, I, just the pro- 
per height to catch the next tooth of the 
wheel, as is shown in fig. 4 : this operation 
moves the paper forward just the proper 
space to write another line. One of the 
rises of the pentagraph is to reduce the 
writing to half the sjze that it is made on 
the brass shelf, whereby double the number 
of lines are contained on a slip of paper that 
would be if written the full size, and the 
lines are but half the length, so that room is 
left at the ends of the rollers for the rachet 
wheel and milled nuts. The rollers will 
hold a slip of thin paper twenty inches long, 
and contain 100 lines, each of two inches 
long : this will contain a considerable quan- 
tity of information, and when it is all writ- 
ten, and rolled upon the roll, I, the lever, 
k, (fig. 2) of the other roller will be ex- 
posed to view ; then the pentagraph is to 
be lifted up upon its hinge, g-, and the lever 
raised up by putting the nail under the end 
of it: this releases one end of the paper; 
and by pulling it the other roll will be un- 
W'ound ; and when the small lever of that 
roller is taken upj the paper will be quite 
loose ; another piece will be fixed with 
equal ease, by first fixing it to the roll H, 
and rolling it upon it, and then fastening it 
to the other. If at any time any particu- 
lar line of the writing is wanted, it will be 
easily brought into view, by turning the 
rollers by their nuts, I, m. 
This instrument would be particularly 
useful to persons who have occasion to make 
memorandums while oi) horseback, or tra- 
velling in a coach, as any degree ofpressure 
may be given upon the brass shelf while 
writing, so as to avoid being disturbed by 
the most violent shocks, which cannot be 
dpne upon common paper for fear of break- 
ing the pencil point, or of piercing the 
paper by it. Its use to blind people wlw 
have learned to write is very obvious. 
SCRATCH, in the language of the salt- 
workers of our country, the name of a cal- 
careous, earthy, or stony substance, which 
separates from sea-water in boiling it for 
salt. This forms a thick crust, in a few days, 
on the sides and bottoms of the pans, which 
they are forced to be at the pains of taking- 
off once in a week, or ten days, otherwise 
the pans burn away and are destroyed. 
SCREW, one of the five mechanical 
powers. See Mechanics. 
f • J 
