1864.] Astronomy. 445 
the last opposition with an accuracy never before attempted. Mr. 
De la Rue, far from being content with the admirable results which 
he had obtained in celestial photography, had made additional and 
successful efforts for its further improvement. And, finally, the sur- 
face of the sun had been the subject of study to various astronomers, 
best fitted by their intelligence, their sharp-sightedness, and their 
command of appropriate apparatus, to extend our knowledge of this 
marvellous body. Nor are the different Observatories, both public and 
private, to be passed over in this brief review. At Greenwich the 
great Equatorial was employed during the past year in observations of 
the fixed lines of the stellar spectra, and recently the prism apparatus 
has been provisionally altered, so that, instead of producing astigmatic 
breadth of the spectrum by the unequal refractions of a conical pencil 
at the two sides of the prism, a pencil of rays made parallel by a 
lens traverses the prism, and, after being made convergent by a 
second lens, is made astigmatic by a cylindrical lens. The defini- 
tion of lines appears to be improved, and the facility of measuring 
them increased. The same equatorial has also been used in ob- 
servations of the Nebula of Orion, with results which show that the 
older drawing printed by Sir J. Herschel in the Results of the Cape 
Observations, 1847, is a more accurate representation of the appear- 
ance now presented by the Nebula, than the more recent drawing by 
Professor G. P. Bond. It is the opinion of the observers that Sir 
John Herschel’s drawing represents as accurately as perhaps any 
drawing can, the appearances presented about the so-called jaws. 
According to this, there appears to be no valid reason for the suppo- 
sition that the Nebula of Orion has been slowly altering its character 
of late years. At the Royal Observatory, Edinburgh, where time-sig- 
nalling is one of the specialities, some important extensions have been 
made, and there were at the beginning of this session no less than 
seven separate time-gun signals fired in different cities in England 
and Scotland directly from the Royal Observatory, Edinburgh, whilst 
five more cities were in pretty active preparation. For short lines the 
system of explosion, based on the use of Professor Wheatstone’s mag- 
neto-exploder and Mr. Abel’s fuse, was found to answer perfectly, and 
it was also frequently successful between Edinburgh and Neweastle, a 
distance of 120 miles; but when the insulation was bad, by reason of fogs, 
the high intensity of the magnetic currents caused their loss and dissi- 
pation before reaching their destination. Hence a system was devised 
by which a current of electricity of low intensity was despatched 
along the line; and this, on reaching the town where the time-gun 
was placed, automatically liberated a current of magneto-electricity, 
which then passed along a covered wire for the short distance up to 
the time-gun. In the twelfth volume of printed Astronomical Obser- 
vations lately issued from this Observatory, an addition of an unusual 
character is worthy of notice, namely, four plates photographic and 
one photoglyphic ; the latter especially prepared for the occasion by 
Mr. Fox Talbot, the inventor both of photography and photoglyphy. 
The scientific reason for the introduction of these plates, which are 
highly magnified portions of some of the Teneriffe photographs of 
2H 2 
