448 REPORT—1905. 
promote and aid all branches of knowledge, and that steps are now being taken to 
prosecute the detailed topographical survey and provide good maps. 
To many people one map is as good as another. They do not pause to consider 
on what it is based, or what degree of accuracy it probably possesses, but so long 
as there is a map they are satisfied. 
A vast number of existing maps are compiled from the roughest materials: 
in partly occupied countries, from drawings of small areas placed together as can 
best be done, by means of places here and there whose relative positions are fairly 
known by distances along roads, with perhaps in some cases angles and astro- 
nomical positions; in less civilised parts by routes of travellers laid down by 
estimation of the distance traversed and direction of march, checked perhaps by a 
few astronomical observations of more or less value as the traveller possesses or 
does not possess the necessary skill. 
The compilers of such a map have a difficult task. Discrepancies are, of course, 
multitudinous. Nothing agrees, and one has to accept, reject, and adjust as best 
he can on his own responsibility and with what knowledge he can procure of the 
respective reliability of each author. 
Happy is he if he has even a few positions in his map which have been 
properly determined, as between them he is saved from the constantly increasing 
errors of adding one little area to another, which if carried on indefinitely culmi- 
nates in great errors. 
Of course such maps are of no practical use, save as giving a very general 
idea of a country, and when required by the administrator or traveller lead to 
endless mistakes and annoyances. 
The feature of our globe which is now, broadly speaking, most accurately laid 
down is the coast-line, The safety of navigation has caused general marine 
surveys to be carried on all over the world during the nineteenth century, which 
have finally determined the position and shape of the boundaries of the sea. 
These surveys, executed for the most part by skilled naval officers with proper 
instrumental outfit, and supplied especially with reliable chronometers, and based 
upon frequent carefully determined astronomical positions, have resulted in this 
boundary line being delineated with an accuracy, so far as its absolute position is 
concerned, far in advance of any other main feature in maps. 
Here I may perhaps explain to those unversed in these matters why this 
is so. 
The position of any spot on the earth’s surface can be ascertained in two 
ways: either by careful measurement by means of an accurate system of triangles 
from another spot already fixed, or by independent observations of the heavenly 
bodies and calculations from them, which give the precise latitude and longitude 
of the place. The former is suitable for positions inland, but entails much time 
and labour, and is only adopted when a perfect map is to be made, for which it is 
the indispensable foundation. The latter can be carried on from a ship, and 
under most circumstances only from a ship, because of the limitations of the 
methods of determinating longitudes. 
Longitude can now be satisfactorily and rapidly ascertained in two ways: by 
the electric telegraph or by use of chronometers. 
The places served by the electric telegraph are still few, and its use is there- 
fore restricted ; but the chronometer has been in working use for over a hundred 
ears. 
qv This instrument, which is merely a watch of especial construction, will only 
keep a steady rate when it is undisturbed by irregular shocks or motions, 
No means have yet been found for transporting a chronometer on land with- 
out upsetting its regularity, and therefore rendering it useless; but on board a 
ship it can be so suspended and stowed as to prevent its being disturbed by any 
ordinary movements of or in the ship. The accurate time of any place departed 
from, ascertained by astronomical observations, can therefore be carried about on 
board ship for considerable periods, and by comparison with the local time, also 
determined by sextant observations of the heavenly bodies, at any required spot on 
the coast, the difference of longitude is at once obtained with very small limits of 
