also the direction of the wind (both of which affect the instrument), and noted down.

Generally the rising of the barometer presages fair weather, and its falling, rain, snow, or high winds. If the fall be rapid, the storm will be violent, but of short duration; if the fall be slow, it will be less violent, but of longer continuance. No great storm ever set in with a rising barometer.

Great elevations in summer are attended with fine dry weather; great depressions with storms of wind and rain, with thunder and heat; cold, unseasonable weather usually succeeds these depressions.

Great elevations in winter, after a gale from the south-west with rain, are usually followed with a clear sky, and sharp white frosts; great depressions being on a thaw.

A fall of the barometer, with a south wind, is followed by rain in greater or less quantities.

A fall of the barometer, sudden and considerable, with the wind due west, indicates a violent storm from the north or northwest, during which the mercury will rise to its former height.

A steady and considerable fall of the barometer during an east wind denotes that the wind will go around to the south, unless a heavy fall of rain or snow immediately follow.

A falling barometer, with the wind at north, brings the worst kind of weather; in summer rain and gales follow, in spring deep snows and frosts.

This is of rare occurrence.

If, after a storm of wind and rain, the barometer remains steady at the point to which it had fallen, severe weather may follow, without a change of the wind; but on the rising of the barometer a change of wind may be expected.

The barometric column usually stands higher with easterly than it does with westerly winds; and with those from the polar regions higher than with those from the direction of the equator, In the tropical regions the variations are not so great as north or south of them, and are greater in winter than in summer.

HOW TO KEEP THE LOG BOOK.

The log book is a journal of what transpires on board ship. Over the first column is marked the letter H., standing for the hours of the day and night, the figures below it running consecutively from midnight to noon (1 to 12), and then from noon to midnight (1 to 12), making the same divisions of the 24 hours as are used on shore. (The log book is kept in civil time now, instead of the old method of sea time.)

Over the next column will be found the letter " K.," standing for miles, or, as they are called nautically, "knots."

Adjoining will be seen the letter " F.," meaning furlongs; and here I desire to explain that a furlong of distance recorded in a log book means one-eighth of a knot, or mile. Suppose the ship had sailed by the patent log 10 miles and a half; it would be entered in the log book as 10 knots and 4 furlongs. When the courses and distances are footed for the various courses, the furlongs are added and divided by 8, and the answer carried to the column of knots.

Following along to the right we next find the word "Courses," under which heading, and against the hour, will be noted the course of the ship by the compass on board. Every time the ship's course is changed it must be recorded in the log book. If the course is altered between the hours, then draw a line across the page between the rulings to allow for the length of time the ship was on such course over the hour, distance made, course sailed, direction of wind, etc.

We next come to the column of "Leeway." In this column will be jotted down the amount of leeway the ship makes, determined by the officer of the watch.

The next two columns are for the standing of the thermometer and barometer.

The last column is headed "Remarks," and under this head will be recorded all matters of importance occurring on board, such as meeting with vessels, carrying away of sails and spars, state of the weather, accidents to the crew, work progressing on board, etc., etc.

Half-way between midnight and midnight in the log book (noon), will be seen the following headings, connected with red rulings: Course-Distance-Diff. of Lat.-Departure-Lat. by D. R.-Lat. by Obs.- Variation-Diff. of Long.-Long. by D. R. and Long. by Obs.

We will now take them up in their order in dealing with them. 1st. "Course."-Having perhaps sailed several courses since the noon of the day preceding, the idea is (explained under heading of Dead Reckoning) to ascertain the bearing of the ship from the position of the previous day, which is considered as the "Course made good."

2d. "Distance."--On the line of the bearing of the ship from the position last calculated to the point arrived at, the distance is considered as the "Distance made good."

3d. "Diff of Lat."-In this space is to be entered the amount of latitude between the position last calculated and the position arrived at.

4th. "Departure."-Under this heading will be noted the number of departure miles (knots) the ship is either east or west of the place last recorded.

5th. "Lat. by D. R."-After applying the difference of latitude made, to the latitude of the ship on the previous day, we obtain the latitude of the ship by dead reckoning, and the same is marked under the above heading.

6th. "Lat. by Obs."-Latitude by observation is calculated at noon and entered in this column.

7th. "Variation."-The variations used on the different courses are to be shown under this heading.

8th. "Diff. of Long."-The number of longitude miles made (estimated by using the middle latitude as a course in Table 2, together with the whole departure), finds a place here.

9th."Long. by D. R."-The Longitude by dead reckoning is found by traverse table, by applying the difference of longitude made to the longitude of the ship's place on the preceding day.

10th. "Long. by Obs."-The longitude by observation at noon is calculated by chronometer sights worked either in the morning or afternoon, and then carried forward or back to noon by the employment of a traverse table.

EXPLANATION.

Suppose that we should obtain a chronometer sight at 8 o'clock in the morning, and determine our longitude at that time. Between the time of this sight and noon 4 hours elapse, and, in order to ascertain our longitude when noon arrives, all we have to do is to correct the courses sailed since 8 o'clock, select from Table 2 the departure belonging to them, turn it into longitude miles for the parallel of latitude sailing on, and apply this difference of longitude to the longitude of the ship at 8 o'clock that morning.

Of course, this will not be exactly the longitude by observation, but it will be it so nearly that for practical purposes it can be considered as such.

Again, suppose that no observation was secured during the morning, but that a sight was obtained at 4 o'clock in the afternoon, and we wish to carry our longitude back to noon, in order to check the longitude determined by dead reckoning at that time, all we have to do is to find the departure, as before, that the ship has made since noon, and apply it to the longitude found by observation at 4 o'clock P. M.

See following examples:

TO CARRY LONGITUDE FORward.

At 8 o'clock in the morning, by a chronometer sight, the ship is in the longitude of 70° 30′ West. She then sails S. E. (corrected course) 40 miles up to noon. Ship on the parallel of 41° North.

S. E. 40 miles, Table 2, gives 28.3 miles of departure. 28.3 miles of departure, parallel of 41°38 miles of longitude.

TO CARRY LONGITUDE BACK.

At 4 o'clock in the afternoon, by a chronometer sight, the ship

is in the longitude of 64° 50' West. rected course) 50 miles since noon. North.

She has sailed N. W. (corShip on the parallel of 38°

N. W. 50 miles, Table 2, gives 35-4 miles of departure. 35.4 miles of departure, parallel of 38°-45 miles of longitude

The difference of longitude is subtracted from the longitude at 4 P. M., because at noon the ship was 45 miles to the eastward of her afternoon position.

Never ditto figures in the log book.

Where the same course and wind is continuous, always use ditto marks.

CHARTS.

SIGNS AND ABBREVIATIONS USED, SHOWING QUALITY OF BOTTOM.

black-blk.

coral-crl. ground-grd. red―rd. speckled-spk.

brown-br.

rock-r.
rotten-rot.
sand-8.

stiff-8tf.

stones-st.

weed-wd.

white-w. or wh.

gray-gy. ooze-02. clay-cl. gravel-g. oysters-oys. shells-sh. coarse-c. or co. green-gn. pebbles-peb. soft.-8ft. yellow-y.

Buoys are marked: B. (black); Cheq. (checquered); H. S. (horizontal stripes); R. (red); W. (white); B. W. (black and white); B. R. (black and red); R. W. (red and white); V. S. (vertical stripes).

A green buoy indicates the position of a wreck.

BUOYAGE ON THE COAST OF THE UNITED STATES.-In approaching a channel from seaward leave red buoys with even numbers