Elementary arithmetic, with brief notices of its history... by Robert Potts.

14
The eight points in each of the four quadrants are expressed by
means of the initial letters of the four cardinal points. Beginning at
the north, the following are the successive points in the quadrant
between the north and east points:-N., N. byE., N.N.E., N.E. by N.,,
N.E., N.E. by E., E.N.E., E. by N.; next, the points between the
east and south points, E., E. by S., E.S.E., S.E. by E., S.E., S.E. by
S., S.S.E., S. by E.; thirdly, the points between the south and west
points, S., S. byW., S.S.W., S.W.byS., S.V., S.'W. by V., W.S.W.,
WV. by S.; fourthly, the points between the west and north points;.
W., W. by N., W.N.W., N.WV. by WV., N.W., N.W. by N., N.N.W.;
N. by VW.
MEASURES OF TIME.
9. The following table exhibits the ordinary divisions of time:
60 seconds are equal to 1 minute.
60 minutes,, 1 hour.
24 hours,, 1 clay,
7 days,, 1 week
4 weeks,, 1 month.
12 months,, 1 year.
or 365 days 1 Julian year.
Common years consist of 365 days, and leap years, which happen
every four years, consist of 366 days. The calendar months, January,
March, May, July, August, October, December, consist each of
thirty-one days.. The months of April, June, September, anc
November, each of thirty days, and the month of February of twentyeight days, except in leap years, when it consists of twenty-nine days.
This year happens every fourth year, with the omission of three in
every period of 400 years. The sexagesimal division of the hour, the
minute, &c., most probably had its origin in the sexagesimal division
of the circumference of the circle.
If the dividend denote the units of effect produced by an agent in
a given number of units of time, then the quotient arising from
dividing the units of effect by the units of time will denote the effect
produced in one unit of time.
If the dividend denote units of distance and the divisor units of
time, the quotient will denote the number of units of distance which
correspond to one unit of time. As if a body move over uniformly
100 feet in four seconds of time, then the quotient, twenty-five feet,
is moved over in one second of time. The distance moved over by a
body in an unit of time is called the velocity of the body.
If the dividend denote units of distance, and the divisor denote the
distance moved over in one unit of time, the quotient will denote thc
number of units of time in which the body will move over that
distance. If a body move over 100 feet at the rate of twenty-five feet
in one second of time, then the quotient of 100- 25 denotes four
seconds, the time in which the body moves over 100 feet.