820 
SCIENTIFIC BOOKS. 
Topographic Surveying, Including Geographic, 
Exploratory and Military Mapping. By 
Herpert M. Witson, U.S. Geological Sur- 
vey. New York, John Wiley & Sons. 1900. 
205 Figures. 
It is always a source of great satisfaction in 
picking up a book to know that the author by 
training and experience is qualified to speak 
with authority on the subject therein dis- 
cussed. In the case of the book under review 
we have as its writer a graduate of one of our 
best schools of engineering, who afterwards 
served an apprenticeship under Mr. Henry 
Gannett, the master topographer, and then, 
after spending considerable time abroad, be- 
came one of the Division Chiefs of the Geolog- 
ical Survey. 
Every feature of topographic work is taken 
up, treated exhaustively, and with the aid of 
illustrations and tables left in the shape deemed 
the most serviceable to the student. The 
descriptions of instruments and their adjust- 
ments are scattered through the book and the 
tables aré inserted at the point where reference 
to them is first made. Thisis not the usual 
practice, and its practicability is a question of 
personal preference. Ordinarily we look in 
the back of the book for all tables and expect 
to find the first pages devoted to the descrip- 
tion of instruments. 
An important topic, seldom referred to, that 
is found in this treatise is the way in which to 
equip a party for field work, including the 
supplies needed, medicines that should be pro- 
vided, and also suggestions as to how to look 
after the details of camp life. In this connec- 
tion it might be suggested that space is given 
to some matters of trifling importance. How- 
ever, the severest criticism that suggests itself 
is the frequent comparison of the work of the 
U. S. Coast and Geodetic Survey with that of 
‘the Geological Survey. This contrasting places 
the relative accuracy and cost in a misleading 
light and should not be so presented by an 
official of either. organization. Then, too, the 
most expensive work of the Coast Survey has 
been to a great extent experimental, and 
many organizations have profited by the les- 
sons thus learned—none more so than itself. 
SCIENCE. 
[N.S. Vou. XIII. No. 334. 
As, for example, the work of Professor Wood- 
ward, which resulted in perfecting the tape- 
line base-measuring system whereby it was 
possible for a single party in the Coast Survey 
to measure nine bases in a single season. A 
wrong impression is given in comparing cost 
and accuracy, except when great emphasis is 
put on the fact that the cost increases rapidly 
with the accuracy—apparently out of reason- 
able proportion. If we say that one party can 
execute a primary triangulation ata cost of 
90 cts. a square mile with a probable error of 
one-tenth of a foot for each side of this square 
while another charges $30 for a square mile 
and secures a probable error of three-hun- 
dredths of a foot, it looks as though we were 
paying more than thirty times as much to se- 
sure a probable error one-fourth as great. A 
still greater cause for comment is the state- 
ment that while both organizations demand 
the same degree of precision in precise level- 
ing, one costs $10 a mile, while the other costs 
only $5. 
It is far from the purpose of this review to 
question the accuracy of these statements, but 
the opinion is held that such comparisons create 
wrong impressions ard react upon the author. 
It is believed that the author is in error when 
he says that in the topographic survey of the 
District of Columbia no system of bench marks 
was left in the course of the leveling, also that 
the St. Albans base was measured with the sec- 
ondary apparatus, and that any form of tape- 
stretcher is more quickly manipulated than that 
used by the Coast Survey. The reason for re- 
ferring to the matters just mentioned is that in 
the eyes of many they mar a book otherwise 
most excellent, and in the main practically 
beyond improvement. 
It is safe to say that there is not a book on 
topography in the English language, or perhaps 
in any other language, that gives with such 
clearness and discrimination the amount of de- 
tail required for maps intended for various pur- 
poses, and the simplest and quickest methods 
for securing the necessary data. For this rea- 
son it is believed that it is eminently fitted for 
use as a text-book—a rare quality in techni- 
cal treatises—as well as for a handbook for 
those actively engaged in topographic work. 
