238 
BRITISH AND FOREIGN PREPARATIONS FOR THE 
TRANSIT OF VENUS. 
By RICHARD A. PKOCTOR, B.A. (Cambridge), 
HONORARY FELLOW OE KING’S COLLEGE, LONDON 5 AUTHOR OF “THE SUN,” 
“THE MOON,” “SATURN,” &C. 
O N December 9 of this year the most important astrono- 
mical event of the present century will take place. 
Venus will pass in transit across the face of the sun, affording 
thus the means of determining her own distance and thence 
the distance of the sun, the fundamental element of dimen- 
sional astronomy. It is true that another transit will occur 
eight years later, yet the circumstances not being then so 
favourable as they will be next December, the transit of the 
present year retains its position as the most noteworthy astrono- 
mical event of the nineteenth century. Most of the readers 
of the Popular Science Review are doubtless aware that the 
circumstances of the two transits have been the occasion of 
considerable controversy (in which I have unfortunately felt it 
my duty to take a large share) ; and some may fear that the 
circumstances of the controversy are to form the subject of the 
present paper. That, however, is not my purpose. Controversy 
can only be justified when some useful purpose may be fulfilled 
by means of it, as the establishing of some new truth or the 
recognition of some new method of research. When there is 
no such reason for discussion or argument the true lover of 
science is bound to avoid controversy, as necessarily leading 
to mischievous results, uncompensated (in the case supposed) 
by any gain either to knowledge or to our means of acquiring 
knowledge. I do not know, indeed, that controversy is justified 
even where it tends to establish some new truth, if that truth 
is one which must in the long run make good its ground ; in 
such a case (as, for example, in the case of my views respecting 
the constitution of the heavens) I prefer, for my own part, to 
let the matter bide its time. But in the controversy about the 
