Orwell Astronomical Society (Ipswich)
The Solar Eclipse Of 15 March 1858
Some solar eclipses are total, occurring when the Moon appears sufficiently large to obscure the Sun completely, i.e. the ratio of the apparent diameter of the Moon to that of the Sun is one or more. The ratio is known as the eclipse magnitude; its maximum value is around 1.08. At other times, the Moon appears too small to completely cover the Sun and leaves a ring of the Sun's surface (photosphere) visible: in this case, the eclipse magnitude is less than one (the minimum possible value is around 0.9). Such eclipses are known as annular.
It is possible for the Moon and Sun to appear almost exactly the same size, with an eclipse magnitude close to 1.0, in which case the eclipse could be either total or annular. One such eclipse was predicted to cross England on 15 March 1858, when the eclipse magnitude was predicted to be 0.9996. The Astronomer Royal, George Airy (1801-1892, in office 1835-81) described it as the most remarkable eclipse of the Sun that will be visible in this country during the present century. It was expected that the phenomenon of Baily's Beads (where the Sun shines through valleys on the edge of the lunar disc, named in honour of Francis Baily (1774-1844)) would be seen around the entire circumference of the Moon, although probably for less than a quarter of a minute. The ground track of the Moon's shadow was unusually narrow, only about a mile wide. It crossed England from Lyme Regis on the Dorset coast to the Lincolnshire coast of The Wash. Airy published twenty-two observing suggestions (see appendix at the end of this piece) but, given the limits of nineteenth century photography, he doubted that Baily's Beads could be photographed, on account of the extreme rapidity of the change of appearances. He went further and advised observers not to attempt to make records near or during annularity, but to endeavour to impress observations on your memory as well as you can.
The Royal Observatory sent observing parties to:-
Cloud and rain prevented observations, In regard to all its real objects, the expedition failed entirely . However, photometric observations of the eclipse were taken at Greenwich by Edward John Hallam under the direction of G Dunkin .
Publicity around the unusual nature of the event generated interest from all sorts of observers, casual, dedicated and professional. Thirty-six observing reports were collected and presented at meetings of the Royal Astronomical Society (RAS) held on 09 April and 14 May 1858  and subsequently retained in the Royal Greenwich Observatory archives. Reports came in from:-
James Challis, at Cambridge, gave the following beginning and end times of the eclipse (in GMAT , a timescale twelve hours behind GMT, avoiding a change of date in the middle of a night-time observing session):
Reports of the observations taken at Ipswich appear on pages 193-4 of the report.
Observed at Ipswich, Suffolk, by C Stuart, Esq
On the 7th March, I began taking altitudes of the sun, and continued them at intervals during the week to ascertain the rate of the clock and watch.
The calculated time of the beginning of the eclipse was 23h 48m 6s Ipswich mean time.
At 23h 47m the wavy light seen upon the circumference of the sun was certainly more fluctuating and unsteady at the place where the first contact of the moon with the sun was to take place than at any other part of the sun’s edge.
At 23h 48m a small cloud obscured the sun; the eclipse had not then commenced. At 23h 48m 28s the cloud had passed over, and the eclipse was seen to have begun some seconds; and I have no doubt the contact would have been seen to have taken place at the exact calculated time, and also that the time shown by the clock was correct.
At 23h 43m a prominence, or lunar mountain, was distinctly visible on the lower part of the moon, and upon consulting a map of the moon this evening, I find it is the one named Skickardus .
At 23h 57m the light from the sun was very distinctly seen within the edges, and slightly illuminating the dark body of the moon for a short distance, and had the appearance at its termination of three faint bands or fringes of light parallel with the edge of the moon; my impression at the time was that the solar light was inflected by a rare lunar atmosphere, however doubtful. It was in the light passing inwards along the convex surface of the moon that the before-mentioned lunar mountain was situated; it did not appear to me directly on the edge, but a little inside of it, but still high enough for the top to be beyond the edge, and appear in dark relief upon the sun’s disk. I have been in the habit of observing the moon for years under all its phases with achromatic and reflecting telescopes of various sizes and powers, but never was more gratified than on viewing this lunar mountain under such circumstances.
At 0h 29m 26s the moon’s limb was in contact with the edge of the first spot; at 0h 30m 24s it was covered; thus giving its bisection 0h 29m 55s.
At 0h 34m 35s the moon’s limb was in contact with the large group of spots; at 0h 39m 30s the whole group was covered. Clouds prevented the exact time of their reappearance being noted down.
At 0h 45m the clouds began to increase, but still were sufficiently broken at intervals to get several good views of the eclipse, particularly at the greatest obscuration, which was seen to much advantage and gratification by very great numbers of persons. At 1h 49m the clouds became one dense mass, and all further observations were at an end.
The telescope I used (which I mounted equatorially) is an achromatic of 34 inches (86cm) focal length, and only 1⅞ inch (48mm) aperture, with a power of 35; field of view, 50' ; but a most excellent defining one, and I used it in preference to another achromatic of 2¾ inches (70mm) aperture and 46 inches (1.17m) focal length, or a 5-foot (1.52m) reflector with a 5-inch (125mm) aperture.
As the eclipse proceeded, I took some measures with a sextant of the angle between the cusps, but upon examining them since, I think they are too faulty to copy out, and of no value.
Elm Street, Ipswich, Suffolk.
Charles Stuart, a printer or printer's compositor, was born in Ipswich in 1794 or 1796 and, according to census records and the 1844 issue of Whites Directory, lived at 20 Elm Street in the town from at least 1841 to 1871. He retained the same housekeeper/servant (Emily Smith, born in Shrewsbury around 1832) for over twenty years. According to official probate records he died in Ipswich on 18 December 1872. He seems not to have married as he was not related to either of his two executors, although all three shared the same trade. Number 20, like the nearby St Mary at Elms Church, is located on the north side of Elm Street, but it lies east of the junction with Museum Street whereas the church is to the west. Charles could have set up his telescope in St Mary's churchyard as there is a reference to very great numbers of persons at 0h 45m. He is not recorded as a fellow of the Royal Astronomical Society, putting him in the category of casual observers.
During the May meeting of the RAS, it was announced that the following photographs of the eclipse would be exhibited at the next meeting, on 11 June 1858:-
The images were included in the Royal Greenwich Observatory archive and are now held by the Cambridge University Library . Two are reproduced below.
Below left is an image of Cade. Next to it is a photograph by Cade, taken around mid-eclipse, with some cloud visible. On the right is the image captured by Sherlock, near the end of the eclipse. (Note that the orientation of the right hand image is not faithful to the actual event; this is so that the card upon which the image is mounted, visible in the full frame but not in the thumbnail, is orientated appropriately.) See  for image credits.
Cade was born in London on 07 June 1820. In 1842, he married Maria Underwood in Aldersgate, London and subsequently came to Ipswich and worked as a jeweller, watchmaker and engraver from premises at 2 Fore Street. Possibly as a result of a meeting with the early pioneer (and possible inventor) of the wet plate collodion photographic process, Frederick Scott Archer (1813-57), in 1854 Cade had moved to nearby 10 Orwell Place (also known locally as The Wash) where a portrait studio was established . Cade advertised that he was able to record country houses, gardens, statues, works of art and agricultural equipment. By 1873, the business was sufficiently successful that it was relocated to 4 Westgate Street  although the Cade family continued to live at Orwell Place. Cade's second son, Alfred Henry (1843-1927), took over the business in April 1879 . Robert Cade died in London at the comparatively early age of 59 on 22 October 1879 and is buried in Ipswich Cemetery. As far as is known, the eclipse of 1858 was his only venture in astronomy.
To put the images into the context of photographic history, the first type of photograph, the daguerreotype, first appeared in 1839-40 and William Henry Fox Talbot's calotype process was announced in 1841. The details of the wet plate collodion process publicly appeared in The Chemist in March 1851. In the astronomical field, the first photograph of the Sun is said to have been a daguerreotype made on 02 April 1845 by the French physicists Louis Fizeau (1819-96) and Lion Foucault (1819-68). The first successful solar eclipse photograph was secured six years later (seven years before the eclipse that is the subject of this paper) on 28 July 1851. Johann Julius Friedrich Berkowski mounted a 6-cm (27⅓ inch) aperture refracting telescope on the 15.8-cm (6¼ inch) aperture Fraunhofer heliometer of the Royal Observatory, Königsberg, Prussia (now Kalinigrad, Russia) and it was used to obtain a one minute 24 second exposure of a daguerreotype plate during the three minutes and 41 seconds of totality .
Locally, in East Anglia, the Canon of Ely Cathedral, William Selwyn (1806-75), employed a local photographer, John Allan Pershouse Titterton (1830-1914), to take images of the Sun on clear days from 1863 to 1874 . The observatory was near Ely Cathedral and, possibly, in Selwyn's own garden. The images captured cover most of solar cycle 11, which ran from March 1867 to December 1878. A description of the instrument from 1876 refers to a six inch (152 mm) aperture instrument by Slater . Selwyn, who was known for his gently humorous wit, named the instrument an Heliautograph, an allusion to the concept that the Sun would sign its own autograph .
ANNULAR ECLIPSE OF THE SUN, 1858, MARCH 14-15,
The following suggestions for observation of the eclipse are not offered as by any means complete, but as presenting grounds for consideration, which may tend to direct observers in deciding on the employment of the means which they may possess.
I. Observations not requiring Instruments.
- As the eclipse advances, it is desirable to obtain some notion or measure of the degree of darkness.
- At what distance from the eye can a book or paper, exhibiting type of different sizes, be read?
- Hold up a lighted candle nearly between the sun and your eye. At how many sun-breadths' distance from the sun can the flame be seen?
- If you are in an elevated position, remark the changes of colour and appearance of the surrounding objects in the landscape.
- If you see the spots of light formed by the intersecting shadows of the boughs of trees, remark whether they exhibit the luneform of the sun.
- When the annulus is formed you will probably observe it with a darkened glass; but you are particularly requested to devote one instant (as early as possible) to the verification of this point-viz. when the annular sun is viewed with the naked eye does it appear an annulus or a fully illuminated disc?
II. Optical, Astronomical, and Solar-Physical Observations requiring the Use of Instruments,
- As the eclipse advances, estimate (on the image seen in the telescope) the comparative intensity of the sun's light near the centre of his disc and near his limb.
- For the more critical observations it is desirable that the power of your telescope should be so low as to give you an easy view of the whole breadth of the sun.
- Remark irregularities on the moon's limb.
- As the cusps become very sharp, remark whether they are irregular. For this, and for all the observations near the annular phase, it is necessary that you be provided either with a graduated prismatic shade, or with a succession of shades of different intensity, and that you instantly select the shade which is most agreeable to your eye.
- Remark whether the sun's light extends beyond the intersection of the limbs of sun and moon, so as to make the moon's limb visible beyond that intersection. For this purpose the bright parts of the sun must be put out of the field of view, and the shade must be withdrawn.
- As the annularity approaches and is formed, remark whether Baily's Beads and Strings are formed; whether first formed at points corresponding to large inequalities of the moon's limb; whether they surround the moon; how they form and break. Only an instant can be given to this observation. It is of the utmost importance to be assured that your vision at the instant immediately preceding, especially of the moon's inequalities, is very distinct.
- Remark, as one of the most important observations of the eclipse, whether any red flames are seen on the sun's limb. For this purpose you must withdraw the shade, if you are on the annular track, the instant after formation of the annulus, if you are not on the annular track, as soon as the eye can bear the sun. On the annular track the whole line must be rapidly scrutinized; and when the ring breaks the still illuminated part must be put out of the field, and the moon's dark limb must be surveyed. At places not on the annular track this plan (namely, to exclude the illuminated portion of the disc from the field, and to survey the moon's dark limb) must be followed throughout. It seems not improbable that the best chance of seeing red flames will be obtained at places not on the annular track.
- At the breaking up of the annulus, look for Baily's Beads as before.
- Do not attempt any record during or near the annularity. Endeavour to impress observations on your memory as well as you can. If you have an assistant seated at a table with a chronometer and writing materials, you may give him signals for the register of time; but you must connect the phenomena with the time afterwards.
- A good sextant observer may obtain valuable observations for correction of the lunar tables by measuring the intervals between the points of the bright cusps. The observations will require great nerve, and will be difficult; but where most difficult they will be most valuable.
- It seems doubtful whether any valid photographic record can be made, on account of the extreme rapidity of the change of appearances. Thus, in the neighbourhood of London, the line of cusps will change from the vertical to the horizontal position in about three minutes of time.
- If you have a doubly-refracting prism it will be desirable to make observations on the polarization of the light from the sun's limb. For this purpose, when the lune is narrow, place the prism so as to separate the two images transversely to the limb, and remark which image is brighter. Turn the prism 180 degrees round the visual ray, and repeat the observation. Remark carefully the positions of the prism. The prism may be used with the naked eye, or with the telescope, according to the amount of its angular separation of images.
III. Meteorological Observations.
- For change in intensity of solar radiation, observations with the actinometer or the black-bulb thermometer should be kept up during the eclipse. The latter are most trustworthy when the bulb is inclosed in an exhausted glass sphere.
- The barometer should be repeatedly observed.
- The thermometer should be frequently observed, and the general feelings of cold should be noted.
- Observations of humidity are very important. They should be made by the use either of Daniell's dew-point instrument, or of the wet-bulb thermometer.
G B AIRY.
1858, March 8.
Annual Report by the Astronomer Royal to the Board of Visitors of the Royal Observatory, Greenwich, 5 June, 1858, page 9.
Monthly Notices of the Royal Astronomical Society (MNRAS), vol. 18, pp. 181-213 & 240-252. Available online via the SAO/NASA Astrophysics Data System.
Greenwich Mean Astronomical Time. The system was discontinued on 01 January 1925.
To fit the sequence of timings, this time should be 23h 53m?
50 arcmin (0.83°). The Sun and Moon are around 30 arcmin (0.5°) in diameter and so would be nicely accommodated in the field of view of this telescope.
Image numbered 348 in file.
File reference RGO 6/120.
The image of Cade was kindly provided by Susan Thomas of North Vancouver, BC, a descendant of his. The images of the eclipse are reproduced by kind permission of the Syndics of Cambridge University Library. Classmarks are PR-RGO-00006-00120-000-00002 and PR-RGO-00006-00120-000-00006 for the images by Cade and Sherlock respectively.
Suffolk Post Office Directory, 1869.
Kelly's Ipswich Directory, 1892.
MNRAS, vol. 36, p. 147.
MNRAS, vol. 18, pp. 129-131
Bill Barton, FRAS