a as 
PRESIDENTIAL ADDRESS. . 527 
vould not have been clearly shown if any other method of reproduction had 
been used. 
The older maps were generally engtaved on copper, or sometimes on 
stone, and printed in black and white. Subsequently photographic methods, 
such as the photogravure of the Austrian and the more recent sysoa scale 
French maps, were used, and colour printing is now largely resorted to. 
In some cases the colour-plates are prepared by engraving on copper, 
stone, or zinc. The maps of the United States and Switzerland are 
engraved on copper. In other cases, for instance, the 1-inch Ordnance 
Survey, colour-plates are prepared on stone by transfers and offsets from 
the engraved copper plate. In other cases—e.g., the sy¢an-Scale map of 
France—the colour-plates are prepared by photographic methods. 
For clearness, delicacy of outline, and artistic effect nothing equals 
engraving on copper. It forms also the best basis for colour-printing. 
Unfortunately it is very slow and costly. 
Engraving on stone is quicker and less expensive than copper engraving. 
It is inferior in delicacy to the latter, but some of the best stone engraving 
is‘very good. 
Photographic methods are the most rapid and the cheapest, and with 
care give very fair results. As good examples I may quote the zs4z5y-scale 
maps of Austria, prepared by heliogravure, and the 6-inch maps of the 
Ordnance Survey, prepared by heliozincography, both black and white maps. 
Of colour-printed maps I may instance the new soyeso scale map of 
France prepared by heliogravure, and the 3-inch Ordnance Survey map 
hitherto prepared by photo-etching, although I understand that in future 
the outline will be engraved on copper. 
When rapid reproduction and moderate cost are desired I do not 
hesitate to recommend photographic methods which, although not so good 
as engraving, give, when carefully executed, reasonably good results. 
Opinions differ as to the extent to which colour should be used, the 
modern tendency being to use it very freely. I can hardly be accused of 
prejudice against colour, as during my tenure of office at the Ordnance 
Survey colour-printing was largely developed, but I think it is often over- 
done. I consider that a moderate amount of colour is a great improvement 
toa map. Ground forms, however indicated, can, in my opinion, be better 
shown by colour than in black; it is advantageous also to distinguish water 
by colour, to give prominence to main roads by colouring them, and to 
colour woods and forests, but I do not advocate going much beyond this. 
It is difficult to choose colours which are suitable, distinctive, and har- 
monious, and the more numerous the colours used the greater the difficulty 
of doing so. 
Colour-printing introduces possible sources of error. Colour maps are 
based on a drawing on which all detail to appear on the map is shown. A 
plate is prepared for each colour on which there should be only such detail 
as shall be printed in its particular colour. In preparing this plate there 
is a risk that detail which should appear may be omitted, or that detail be 
‘inserted which should be on another plate, or that the detail may be 
slightly out of position. Again, owing to change of temperature and to 
the varying amount of moisture in the air, paper contracts or expands. 
Registration can rarely be mathematically correct, and with every care 
may sometimes be appreciably out. While with care errors such as I have 
indicated can be minimised so as not appreciably to affect the map, it is 
difficult to ensure that they should be altogther absent. 
To recapitulate my views, I advocate for a topographical map a scale 
between g5t55 and gsq'rau (4 inch to a mile), according to circumstances. 
The scale of survey to be double that of the finished map; ground forms 
to be shown by contours reasonably close together, the exact interval 
depending on the scale of the map and‘the nature of the country, also, if 
