at the bow of the fhip, where the current fitft be-
gins, and acts fairly upon the palate, in preference
to the ftern, where the tumultuous clofing of the
waters caufes a wake, vifible to a great diftance.
The palate D is funk nearly as low as the keel,
that it may not be influenced by the heaping up
of the water and the dafhing of the waves at and
near the water line. The arch K is to afcertain
how many knots or miles fhe would run in one
hour at her then rate of failing. But the gradua-
tions on this arch must be unequal; becaufe the
refiftance of the spring L will increase as it be-
comes more bent, fo that the index will travel
over a greater space from one to five miles than
from five to 12. Laftly, the palate, rod, fpring,
and all the metallic parts of the inftrument, fhould
be covered with a trong varnish, to prevent
ruft from the corrofive quality of the falt water
and fea air. This machine may be confiderably
improved as follows: Let the rod or fpear A B
(fig. 5.) be a round rod of iron or fteel, and in-
ftead of moving on the fulcrum or joint, as at C,
let it pass through and turn freely in a focket,
to which focket the moveable joint must be an
nexed, as reprefented in fig. 6. The rod muft
have a fhoulder to bear on the upper edge of the
focket, to prevent its flipping quite down. The
rod muft alfo pafs through a like focket at F, fig.
5. The joint of the lower focket must be fixed
to the bow of the fhip, and the upper joint or
focket must be connected with the horizontal arm
E. On the top of the uppermoft focket let there
be a fmall circular plate, bearing the 32 points of
he mariner's compafs; and let the top of the rod
AB come through the centre of this plate, fo as
o carry a fmall index upon it, as is reprefented
fig. 7. This fmall index must be fixed to the
op of the rod on a square, fo that by turning the
ndex round the plate, the rod may alfo turn in
the fockets, and of courfe carry the palate D
ound with it; the little index always pointing
na direction with the face of the palate. The
mall compafs plate fhould not be faftened to the
op of the focket, but only fitted tightly on, that
t may be moveable at pleasure. Suppofe then
he intended port to bear SW. from the place of
leparture, the palate must be turned on the foc-
et till the SW. point thereon looks directly to the
hip's bow; fo that the SW. and NE. line on the
ompafs plate may be precifely parallel with the
hip's keel, and in this pofition the plate must re-
main during the whole voyage. Suppofe, then,
he fhip to be failing in the direct courfe of her
ntended voyage, with her bowfprit pointing SW.
Let the little index be brought to the SW. point
in the compafs plate, and the palate D will ne
effarily prefent its broad face toward the port of
leftination; and this it must always be made to
lo, be the fhip's courfe what it may. If, on ac-
ount of unfavourable winds, the fhip is obliged to
leviate from her intended course, the little index
nuft be moved fo many points from the SW. line
of the compass plate as the compafs in the bin-
acle fhall how that the deviates from her true
ourfe; fo that in whatever direction the fhip fhall
ail, the palate D will always look full to the SW.
oint of the horizon, or towards the port of def.
ination, and confequently will prefent only an

oblique furface to the refifting medium, more or lefs oblique as the fhip deviates more or lefs from the true courfe of her voyage. As, therefore, the refiftance of the water will operate lefs upon the palate in an oblique than in a direct pofition, in exact proportion to its obliquity, the index H will not show how many knots the veffel runs in her then courfe, but will indicate how many the gains in the direct line of her intended voyage.Thus, in fig. 9. if the ship's courfe lies in the direction of the line AB, but the can fail by the wind to nearer than AC; fuppofe, then, her progreffive motion fuch as to perform AC equal to five knots or miles in an hour, yet the index H will only point to four knots on the graduated arch, because he gains no more than at that rate on the true line of her voyage, viz. from A to B. Thus will the difference between her real motion and that pointed out by the index be always in proportion to her deviation from her intended port, until the fails in a line at right angles therewith, as AD; in which cafe the palate would prefent only a thin fharp edge to the refifting medium, the preffure of which should not be fufficient to overcome the friction of the machine and the bearing of the fpring L. So that at whatever rate the hip may fail on that line, yet the index will not be affected, fhowing that the gains nothing on her true courfe. In this cafe, and alfo when the veffel is not under way, the action of the fpring L fhould caufe the index to point at O, as reprefented by the dotted lines in fig. 5. and 8. As the truth of this inftrument muft depend on the equal preffure of the refifting medium upon the palate D, according to the ship's velocity, and the proportionable action of the fpring L, there fhould be a pain or fcrew at the joints C and F, fo that the rod may be readily unfhipped and taken in, in order to clean the palate from any foulness it may contract, which would greatly increafe its operation on the index H, and thereby render the graduated arch falfe and uncertain. Further, the fpring L may be expofed too much to injury from the falt water, if fixed on the outfide of the fhip's bow. To remedy this, it may be brought under cover, by conftructing the ma chine, as reprefented by fig. 8. where AB is the rod, C the fulcrum or centre of its motion, D the palate, E the horizontal arm leading through a fmall hole into the forecastle; M is a strong chain fastened at one end to the arm E, and at the other to a rim or barrel of the wheel G, which by means of its teeth gives motion to the femicircle I and index H. The fpring L is fpiral and enclofed in a box or barrel, like the main fpring of a watch. A fall chain is fixed to, and paffing round the barrel, is faftened by the other end to the fuzee W. This fuzee is connected by its teeth with the wheel G, and counteracts the motion of the palate D. N, N, are the two fockets through which the rod AB paffes, and in which it is turned round by means of the little index R. S is the fmall compafs plate, moveable on the top of the upper focket N. The plate S hath an upright rin round its edge, cut into teeth or notches, fo that when the index R is a little raifed up, in order to bring it round to any intended point, it may fall into one of thefe notches, and be detained there;

otherwife