division every 60 minutes. The motion of this wheel is likewise
controlled by the cylinder, W.

It will be seen upon referring to Fig. 7, that there is obtained a
very sharp curve marked by points. We have a general view on
considering the curve itself, and the height in meters is read
directly. The fractions of a meter, as well as the times, are in the
margin. Thus, at the point, a, the apparatus gives at 3 o'clock and
20 minutes a height of tide of 4.28 m. above the level of the lowest
water.

This apparatus might possibly operate well, and yet not be in accord
with the real indications of the float, so it has been judged
necessary to add to it the following control.

Every time the float reaches 3 meters above the level of the lowest
tide, the circuit of one of the lines that is open at this moment
(that of line I, for example) closes at C (Fig. 2), into this new
circuit there is interposed a considerable resistance, W, so that the
energy of the current is weakened to such a point that it in nowise
influences the normal travel of the wheel, r. At the shore station,
there is placed in deviation a galvanoscope, K, whose needle is
deflected. It suffices, then, to take datum points upon the
registering apparatus, upon the wheel, T, and the screw, a, in such
a way as to ascertain the moment at which the stylet, g, is going to
mark 3 meters. At this moment the circuit of the galvanoscope, K, is
closed, and we ascertain whether there is a deviation of the needle.

As the sea generally rises to the height of 3 meters twice a day, it
is possible to control the apparatus twice a day, and this is fully