PRESIDENT’S ADDRESS. 25 
that such velocities must be determined star by star. For the fainter 
stars huge telescopes and spectroscopes of comparatively low dispersion 
must be employed. On this account there is great need in both hemi- 
spheres of a huge reflecting telescope—six to eight feet in aperture— 
devoted almost exclusively to this research. Such a telescope is already 
in preparation at Mount Wilson, in America, for use in the northern 
hemisphere. Let us hope that Professor Pickering’s appeal for a large 
reflector to be mounted in the southern hemisphere will meet with an 
adequate response, and that it will be devoted there to this all-important 
work. 
Conclusion. 
The ancient philosophers were confident in the adequacy of their 
intellectual powers alone to determine the laws of human thought and 
regulate the actions of their fellow men, and they did not hesitate to 
employ the same unsupported means for the solution of the riddle of the 
universe. Every school of philosophy was agreed that some object which 
they could see was a fixed centre of the universe, and the battle was 
fought as to what that centre was. The absence of facts, their entire 
ignorance of methods of exact measurement, did not daunt them, and the 
question furnished them a subject of dispute and fruitless occupation for 
twenty-five centuries. 
But astronomers now recognise that Bradiey’s meridian observations 
at Greenwich, made only 150 years ago, have contributed more to the 
advancement of sidereal astronomy than all the speculations of preceding 
centuries. They have learned the lesson that human knowledge in the 
slowly developing phenomena of sidereal astronomy must be content to 
progress by the accumulating labours of successive generations of men ; 
that progress will be measured for generations yet to come more by the 
amount of honest, well-directed, and systematically discussed observation 
than by the most brilliant speculation ; and that, in observation, concen- 
trated systematic effort on a special thoughtfully selected problem will be 
of more avail than the most brilliant but disconnected work. 
By these means we shall learn more and more of the wonders that 
surround us, and recognise our limitations when measurement and facts 
fail us. 
Huggins’s spectroscope has shown that many nebule are not stars at 
all ; that many well-condensed nebule, as wellas vast patches of nebulous 
light in the sky, are but inchoate masses of luminous gas. Evidence upon 
evidence has accumulated to show that such nebule consist of the matter 
out of which stars (i.e., suns) have been and are being evolved. The 
different types of star spectra form such a complete and gradual sequence 
(from simple spectra resembling those of nebule onwards through types 
of gradually increasing complexity) as to suggest that we have before us, 
written in the cryptograms of these spectra, the complete story of the 
evolution of suns from the inchoate nebula onwards to the most active 
