and you are swimming either by yourself or having hold of a person who cannot swim, then get on your back and float until help comes. Many a man exhausts himself by stemming the billows for the shore on a "back-going" tide and sinks in the effort, when, if he had floated, a boat or other aid might have been obtained.

These instructions apply alike to all circumstances, whether in regard to the roughest sea or smooth water.

A SERIES

OF

QUESTIONS

RELATING TO THE SUBJECTS

TREATED IN THIS VOLUME

It will be noticed that the various Examination Questions that follow have been divided into sections to which have been given the same section numbers as the Instruction Papers to which they refer. No attempt should be made to answer any of the questions until the Instruction Paper having the same section number as the Examination Questions has been carefully studied.

LAKE NAVIGATION

(PART 1)

EXAMINATION QUESTIONS

(1) Define navigation, its aim, and purposes.

(2) (a) How is a position on the earth's surface determined? (b) What do you understand by the first, or prime, meridian?

(3)

Define latitude and longitude and describe how they are measured.

(4) What is (a) difference of latitude? (b) difference of longitude?

(5) (a) What is the difference of latitude between Buffalo, N. Y., and Boston, Mass., the latitude and longitude of the former being, approximately, 42° 52′ N and 78° 53′ W, and of the latter, 42° 22′ N and 71° 3′ W? (b) Find, also, the difference of longitude between the two places expressed in time. (a) Diff. of Lat. = 30'. (b) Diff. of Long.

Ans.

=

31m 20s.

(6) The latitude and longitude of Duluth, Minn., is approximately 46° 46' N and 92° 5' W; the latitude of Philadelphia, Pa., is 39° 53′ N and its longitude is 75° 10' W. Find (a) the difference of latitude and (b) the difference of longitude, expressed in time, between the two places.

(7) If one place is

situated in latitude 5° 2′ S and longitude 172° 45′ E, another in latitude 3° 47' N and