SCIENTIFIC SUMMARY. 
427 
"was this that the objectors said could not be achieved by the plan then pro- 
posed. If new plans had succeeded, during the recent eclipse, in achieving 
that very result the objectors would not have stood corrected. By the use 
of the Rutherfurd grating the chance of success was unquestionably greater 
than it had been in 1875. Moreover, terrestrial conditions during the recent 
eclipse were altogether more* favourable than those of the eclipse to which 
their remarks related. But in reality, notwithstanding the greatly increased 
chances of success, and a marked improvement in the method of attack, the 
attack has failed as completely on this occasion as it failed in 1875. The 
spectrum of the corona has indeed been photographed. No one ever said 
that this could not be done, or even that it involved any difficulty. The 
spectral images of the corona, however, were net shown, even near the sun, 
where we know (from the observations of Eastman, Thomas, and others) 
that they undoubtedly existed. Dr. Draper, Professor Thorpe, and Mr. 
Lockyer all photographed the spectrum of the corona ; but as Mr. Lockyer 
says, who certainly was not disposed to minimize their success, 11 we had 
photographed as continuous a spectrum as if a platinum wire or ball in a 
state of incandescence had been in front of our instrument, instead of a shell 
of hydrogen gas 6' high as in 1869, 10' high as in 1871.” In other words, 
the method entirely failed to do what it had been expected to do, and what 
in 1875 Mr. Lockyer and others had promised for it. We do not doubt that 
the circumstances were in reality far less favourable than they had been in 
1869, 1870, and 1871. For the 1474 line was very faint, f alone of the 
hydrogen lines could be seen, and no observer saw the spectral images (as 
distinguished from the spectral lines ) of the corona at all. But to describe 
the failure of the method, however brought about, as involving the disproof 
of objections formerly urged against it, is absurd in the extreme. The 
objectors said the method would certainly fail in 1875, and it did then fail 
entirely. They were doubtful whether the improved method devised for the 
late eclipse would succeed, and it has not succeeded. Hereafter, under more 
favourable conditions, and with improvements in photographic appliances, a 
method may be devised for obtaining photographs of the spectral images of 
the corona ; but that certainly has not been done yet, nor if it had been done 
would it have shown that the objections urged in 1875 were invalid. The 
validity of these objections was, in fact, demonstrated effectually and defi- 
nitely by the results obtained during the eclipse of that year. 
Polarization of the Corona . — The majority of the observations showed that 
the corona was polarized radially. But Professor Hastings believes that he 
obtained satisfactory evidence of tangential polarization. He explains what 
he saw by the theory that there are ice-crystals in the corona — which, to say 
the least, seems unlikely. 
Heat of the Corona . — By means of his wonderfully delicate heat-measuring 
instrument, the tasimeter, Mr. Edison succeeded in proving that the corona 
emits or reflects an appreciable amount of heat. He was not able to measure 
the heat of the corona, however, in this way, simply because the instrument 
proved to be too delicate. The indicator went quite off the field of view, 
and before it could be brought back totality was over. 
Intra-Mercurial Planet. — Professor Watson and Mr. Swift both recognized 
a star of the 4th magnitude, or rather less, close to Theta Cancri. Watson 
found that it had a recognizable disc with a magnifying power of only 45. 
