The eclipse as seen from Greenwich. (Illustrated London News)
At 4 o'clock in the morning of Monday, March 15th, 1858, James Breen, of the Cambridge Observatory, came out to study the weather prospects for the central solar eclipse due in nine hours' time. The impending eclipse was very unusual. It would not be total, when the occluding Moon appears larger than the Sun, but an annular, when the Moon seems smaller than the Sun. In this case it would be the rarest of eclipses; the annular-total, or 'pearl-ring'. The Moon would appear smaller than the Sun, but only just, and the edge of the Sun would shine through the crags and mountains round the limb of the Moon, creating an effect like a circle of luminous beads. These are the 'Baily's Beads', named for the astronomer Francis Baily, who observed them during an annular eclipse on May 15, 1836. The central phase of total and annular eclipses lasts several minutes, but in a pearl-ring eclipse, centrality is momentary. In this eclipse, the pearl-ring would last 13 seconds, and the zone in which this would be visible was just under 9 miles wide.
Eclipse track, March 15, 1858
Astronomers were preparing for what Professor G. B. Airy, the Astronomer Royal, described as 'the most remarkable eclipse of the Sun that will be visible in this country during the present century'. He had published 22 suggestions for observations that might be taken. It seemed unlikely to him that the moment of annularity could be photographed, 'on account of the extreme rapidity of the change of appearances.' In fact, he advised that observers should not attempt to make records near or during annularity, but to 'endeavour to impress observations on your memory as well as you can.'
At 4 a.m., the weather looked promising. Thin, wispy cirrus clouds allowed a few stars to be visible, and the Sun rose over London into a clear sky. Spectators filled the parks, Primrose Hill, Hampstead Heath, Trafalgar Square, the Monument and the bridges, and the sellers of smoked glass did a roaring trade. At 44 minutes and 55 seconds past 11 a.m. the edge of the Moon touched the south-west limb of the Sun; but the weather had changed.
Fragments of cloud were sweeping across the sky on a west wind, and, as the eclipse progressed, the clouds thickened. By noon, the sky was completely overcast, with a chilly wind, a leaden haze, and a temperature of only 50º F. Still the spectators waited hopefully, and, just after 1 p.m., near the moment of centrality, they were rewarded with a break in the clouds.
An observer on the gallery of St. Paul's described the moment. “Towards one o'clock matters brightened a little, and a general cheer announced that the clouds had broken, and that the eclipse was plainly to be seen. So nearly annular was it at this moment as to appear complete. The whole centre of the Sun was quite black; the luminous ring glistened over nine-tenths of its circumference; and the increasing coldness of the air proved how large a proportion of the solar heat we were being deprived of.”
The track of centrality reached England on the coast at Lyme Regis in Dorset. Clouds had gathered here also, “yet frequently through the fleecy masses fitful gleams of sunshine cast a peculiar light over the sea and hills...The first perceptible appearance of the Moon was observed at 12:15...A deep twilight gradually settled over the face of nature. The darkness slowly increased until 1.8, at which time a peculiar saffron tinge suffused the sea and meadows surrounding the town, whilst the little white marble villas...seemed to have been immersed in some pale yellow liquid. At the darkest time the light here was equivalent to that of a full moonlight night, though the effect produced was very dissimilar from a nocturnal scene.”
A ‘remarkable prominence’ on the Moon during the eclipse, as seen by James Breen with the Northumberland telescope in Cambridge, 12.40 p.m.
At the Cambridge Observatory, James Breen was preparing to observe the eclipse with the Northumberland 20-foot equatorial. 'Nothing could appear more promising than the state of the sky' in the morning, but here also, ominous clouds appeared on the north-western horizon at 11 a.m., and soon filled the sky. However, Breen was able to follow the encroachment of the Moon upon the Sun until eight minutes past noon, when the sky became heavily overcast. The moment of maximum eclipse was 48 minutes away. Then, with three minutes to go, the Sun, now a thread-like crescent, broke through a rift in the clouds.
James Breen took to the telescope. The southern horn, or 'cusp' of the crescent was breaking up into four or five rounded fragments of light, 'evidently the so-called 'Baily's Beads'. 52 seconds later, “the broken points of light on (the northern) cusp were clearly distinguished; 20 seconds later they were noted as 'continually forming': and they remained visible (subject to continual change) until 4 min. past 1 o'clock, when they ceased to appear. By this time the sky had again become cloudy, and it remained so for the next 20 minutes.”
Darkness prevailed during the moment of maximum obscuration, though Breen noted that it was no greater than “previous to a heavy fall of rain. When the beautiful Sun crescent was looked at, struggling through masses of cloud, it appeared scarcely possible that the considerable amount of light which prevailed could proceed from that slender thread of light.”
At the moment of annularity, the fresh north-westerly wind suddenly died down, and 'a universal silence prevailed'. Birds ceased to sing. A flock of crows apparently decided that night had fallen, and flew off to roost. As the sunlight strengthened, farmyard cocks began crowing incessantly, and the crows returned.
‘Baily’s Beads’ observed telescopically by James Breen in Cambridge
Edward J. Lowe, at the Beeston Observatory in Nottinghamshire, was less fortunate. His sky was overcast, with a stiff wind and a gentle but incessant rain. He was eventually granted a glimpse of the eclipse, but not until three minutes after the formation of the annulus. The eclipse darkness was peculiar, “different from that of night...the railway-posts a quarter of a mile off were scarcely visible, and it was impossible to distinguish men from women 200 yards off, whilst a deathlike stillness prevailed...A large mill with whitewashed walls turned of a decided warm yellow colour, apparent to everyone...”
A few people were favoured with clearer skies. John Yeats, at Fotheringay Castle in Northamptonshire, reported; “All the phenomena of an annular eclipse were clearly and beautifully visible...Baily's Beads were perfectly plain at the completion of the annulus, which occurrence took place, according to my observation, at about 70 seconds past one o'clock; it lasted about 80 seconds...the Baily's Beads “like drops of water, appeared on the upper and under sides of the Moon, occupying fully three-fourths of her circumference. Prior to this the upper edge of the Moon seemed dark and rough...There was nothing like intense darkness during the eclipse. I have seen more gloom in a thunderstorm...At twelve o'clock a lady living on the farm suddenly exclaimed, “The cows are coming home to be milked!” and they came, all but one; that followed, however, within the hour. Cocks crowed, birds flew low or fluttered about uneasily...”.
But to thousands, “the great solar eclipse of 1858...proved a great disappointment”. Passengers on eclipse excursion trains from Manchester, Liverpool, and Birmingham returned home. The glimpses of the eclipse they had “rather tended to excite than satisfy curiosity.”