SCIENCE. 
FRIDAY, JUNE 6, 1884. 
COMMENT AND CRITICISM. 
Tue rapid strides made in all departments 
of science, and the fundamental revolutions in 
some of them, have increased the demand of 
the public and of publishers for books which 
shall expound, in clear and simple language, 
the latest discoveries. Yet publishers look at 
such books in some measure askance, unable, 
as a rule, to judge for themselves of their 
probably permanent or ephemeral value, and 
always with a very reasonable fear that they 
will speedily prove antiquated, and become a 
drug in the market. An apparent attempt to 
evade the little financial dilemma which the 
advance of knowledge presents to the vender 
of literary wares has recently been brought to 
our notice. Four books, sent us at one time 
for review, were first examined to see whether 
they were of sufficiently recent date to notice. 
They bore no date. A careful examination 
showed that one of them consisted of lectures 
delivered two or three years ago, but no clew 
to the age of the others could be found. It 
was tolerably evident that the very unusual 
omission was intentional. If intentional, it 
was, to say the least, a deliberate purpose to 
evade the purchaser’s natural and proper ques- 
tion, Does this book represent present knowl- 
edge? We leave to the ‘ Society for the pro- 
motion of Christian knowledge,’ whose imprint 
each of these books bore, to ask itself the ques- 
tion, Is such a practice defensible on the 
srounds of scientific, Christian, or even pagan 
morality ? 
Ir is a question to be considered, whether 
our smaller societies of natural history, to 
whose meetings we desire to call attention in 
the columns of Science, do not make a mis- 
take in having no plan of work towards the 
accomplishment of which they can make a 
No. 70.—1884. 
united effort, instead of pursuing observation 
and discussion almost at random. Larger 
societies in the cities, where publications, and 
even general collections, are attempted, must 
naturally cover a broad field: it is not to these 
that we refer, but to the smaller societies that 
spring up, too often for but a short life, in our 
country towns. ‘The desire for large member- 
ship, and the admission of members to full 
standing without any requirement of work ac- 
complished, seems to us another error. Five 
really industrious members make a very good 
nucleus for a local club. Others can be added 
later, on the assurance of some task of local 
observation actually performed, and of willing- 
ness to co-operate towards some attainable 
end; and beyond this there may, of course, be 
general meetings, as public and as fully at- 
tended as possible, but full membership should 
in all cases mean work done. 
Tue coast-survey has just published a 
‘North-Atlantic track-chart,’ executed with the 
beautiful neatness characteristic of its work, 
‘¢ to illustrate the point, that, in the conic pro- 
jection, the straight line upon the plane surface 
of the chart almost exactly represents the great 
circle contained between its termini, which on 
other projection will do.’’ A reduced facsimile 
of the chart will be found on the next page. 
If this be demonstrated to obtain with sufficient 
closeness for all latitudes and all courses, the 
conic projection, in which a part of the earth 
is represented on a conical surface, tangent 
or secant about the middle latitudes of the re- 
gion represented, should replace the common 
Mercator’s or cylindric projection of ordinary 
sailing-charts, in which great distortion is 
caused by throwing the geographic lines on a 
cylinder tangent to the earth’s equator. 
The advantage usually quoted for the latter 
projection is, that it enables the navigator to 
lay out a course having a constant bearing 
