Wednesday May 2, 1894

M^r Plummer left, having completed his obs^ns for personal equation with the portable Transit in the Transit Pavilion.
Meting of Solar Eclipse Com^ee at the R.A.S. at 3 & 4. Royal Society Soiree.

William Christie, Astronomer Royal

RH says..... This event at the Royal Society - one of their regular soirees or conversazione - was reported in the journal Nature on 10 May 1894 (which, unfortunately, you can only see if you or your institution subscribes - which mine does not). This fantastic image illustrating a Royal Society 'gentleman's conversazione' is from the Daily Graphic in 1890. See more here.

Friday April 20, 1894

Savile Com^ee meeting at 5.45

William Christie, Astronomer Royal

M^r Plummer here to determine longitude of Bidston

Frank Dyson, Chief Assistant

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RH says..... Christie continues with the social side of the Astronomer Royal's post, at the Savile Club, while Dyson was back working with William Plummer of Liverpool Observatory, as he had at the beginning of the year. Christie's report to the Board of Visitors in June 1894 recorded that when Plummer had been at the ROG from the 1st to the 9th of January, “cloudy weather prevented observations" but that when he "again visited Greenwich from April 20 to May 2" he "secured observations on six nights with the small transit in the Transit Pavilion for comparison with the transit-circle observer".

Maunder's perception experiments

RH says..... Since Christie is away on his Easter holidays, and since I am working on a lecture on pre-space age observations of Mars, I thought I would briefly return to the theme of E. Walter Maunder's experiments on perception with the boys of Royal Hospital Schools in Greenwich (see my previous entry for background). Since the scan of his 'Experiments as to the Actuality of the "Canals" observed on Mars' available online has very unclear images, I thought I would rescan them and put them up here. The first shows (top) a photograph of a drawing based on an original by Giovanni Schiaparelli - but with the controversial straight canals replaced by "a number of small irregular markings ... inserted at haphazard" and "river-like marks". This drawing was shown to the boys, and the second image shows photographs of six of their drawings, produced from observations at varying distances from the original. Despite the absence of straight lines, most of the boys - especially those sitting in the middle rows - produced canal-like markings that agreed closely with the schematic Key Map shown at the bottom of the first image. Three boys, in addition, included a short line where Schiaparelli did not - "which we have here called from the name of its disocverer, 'Allen's Canal.'"

Maunder on Mars

RH says..... Time to return to Mars, this time focusing on the views of E. Walter Maunder, the head of the Royal Observatory's Photographic and Spectroscopic Department. Maunder seems to have become involved with the debates about the nature of Mars's surface through meetings of the Royal Astronomical Society and the British Astronomical Association, which he had founded in 1890. Since 1877, discussions had tried to account for the differences between the maps produced in that year's heliostatic opposition (the best possible viewing conditions for Mars) by Giovanni Schiaparelli and Nathanial Green.


















Green, an amateur astronomer but a professional artist and longtime Mars observer with a powerful telescope, had apparently seen something very different from Schiaparelli, the director of Milan's Brera Observatory but a first-time Mars viewer. Maunder essentially sided with his compatriot and initially agreed that it was most likely that the lines seen by Schiaparelli were the boundaries of differently shaded regions. He became interested in how such optical effects might be produced and, in 1902-03 went to the extent of experimenting on the boys of the Royal Hospital Schools, Greenwich (now the buildings of the National Maritime Museum) to see if images of "canals" could be produced when images without lines were viewed at various distances. His 'Experiments as to the Actuality of the "Canals" observed on Mars' concluded that in most cases,

"the canals of Mars ... are simply the integration by the eye of minute details too small to be separately and distinctly defined. It would not therefore be in the least correct to say that the numerous observers who have drawn canals on Mars during the last twenty-five years have drawn what they did not see. On the contrary they have drawn, and drawn truthfully, that which they saw; yet for all that, the canals which they have drawn have no more objective existence than those which our Greenwich boys imagined they saw on the drawings submitted to them."

Saturday February 24, 1894

The crown lens of the 28ⁱⁿ telescope was reversed to the photographic position the separation of the lenses having being reduced to 3.71 in.

William Christie, Astronomer Royal

RH says..... Christie was still trialing the reversable photographic-visual lens of the new 28-inch telescope. Meanwhile, the RGO archives record some of the more regular observations being undertaken with other equatorial telescopes at the Observatory. On this day, observations were made of "Pseudo/Euterpe", probably with the Sheepshanks telescope, and some trial observations of Ursa Major are also recorded. The first was presumably the asteroid or minor planet 27 Euterpe, discovered in 1853 by the British astronomer John Russell Hind, who had been an assistant at the ROG from 1840-44.

Regular work at Greenwich Observatory

RH says.....
When there is little or nothing recorded in the Astronomer Royal's or Chief Assistant's journals we can assume that the regular work of the Observatory went on as usual. The annual publication of the Royal Observatory, Greenwich - Greenwich Observations - demonstrates how large a task regular observing and calculating work was, especially at a time that they felt themselves under-staffed. Christie boasted that despite expanding work in what were new fields for Greenwich - especially astro-photography, spectroscopy, double-star observation and increasing equatorial observations - they also managed to increase the number of regular transit observations.

Between May 1893 and May 1894 the average number of transits observed each day was 31 or, if Sunday was discounted, 36. However, conditions meant that this load was spread unequally and Christie noted that the "very favourable conditions" during February 1894 meant that on three consecutive days 458 transits and 460 zenith distances were observed. This was hard and repetitious manual labour for the observers, especially if we remember all the additional observations that had to be made in order to calculate the various errors that had to be factored into the equally labourious calculations that each set of data prompted.