J. Brit. Astron. Assoc., 109, 6, 1999, p.354

Letters

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Frederick Archenhold

From Mr Brian Manning

I was very interested to read Eric Strach's obituary for Gunter Archenhold because I knew Gunter's younger brother for nearly 50 years, until his death in May 1998. I thought members might be interested to hear a little about him. Although not a BAA member, Frederick, or Fred as he preferred to be known (not to be confused with Gunter's son) did have a connection with the BAA: he told me that he collaborated with Colin Ronan during the war in developing an optical relay system to enable early radar equipment in the bowels of a ship to be seen from the bridge. According to Fred I actually have a 5-inch diameter plano-concave lens from this system.

He was born in Berlin observatory in 1920 and the household must have been quite fascinating. Einstein was a frequent visitor, and they had musical evenings with Einstein playing the cello (his normal instrument was the violin), Fred's older sister playing the violin, Gunter the flute and their mother the piano. As a Jew he was barred from a University education in Germany and taught himself mathematics, no doubt with help from the family, and I am told by his eldest son Simon that he understood relativity theory at an early age and argued with Einstein over aspects of the theory.

Fred was apprenticed to an optical firm in Germany but was warned to leave the country in 1939. He came to this country and was found work by the Quakers with The British Optical Lens Co., a subsidiary of E. Elliott Ltd, a plastics moulders in Birmingham (later in Walsall). He was interned on the Isle of Man from May 1940 to January 1941, when he was able to return to Elliott's. Evidently he was now considered trustworthy because the radar equipment, and a special tank periscope he designed for the amphibious tanks used for the Normandy landings, was obviously top secret. He eventually became a director and was an expert lens designer.

I first met him in the 1950s at the Birmingham Astronomical Society, then the Birmingham Astronomy Group of which I believe he was the instigator. At that time I was experimenting with ruling diffraction gratings and he helped me by producing the very thick aluminium on glass coatings that I needed and at the same time gave me some useful advice on the ruling engine. He had three sons and two daughters. His health declined badly in his last few years when I had many enjoyable telephone conversations with him, which I now greatly miss. In 1991 he went on a cruise liner to see the solar eclipse from off the coast of California, and told me all about it.

There may be some confusion about who attended the Archenhold Observatory centenary, caused by the fact of Gunter's son being Fred and his brother also being Fred. The Fred I knew also attended the Centenary, and laid flowers on his father's grave as he told me. In addition to my own memories I have had help with this letter from Fred's son Simon and Miss Margery Elliott, a daughter of the firm's founder and a former director. Tracing his family, who move around, was difficult and Eric Strach kindly gave me Simon's address and that of Gunter's son.

Brian Manning
Stakenbridge, Churchill, Kidderminster, Worcs.

Roman numerals in chronology

From Mr Peter Macdonald

Soon we will have to accustom ourselves to the shorter strings of letters which will be needed to denote the years in Roman numerals.

On some recent occasions it has been necessary to use ten or more numerals to express dates. Using the current notation, the 'longest' year in this century was 1988 with eleven characters – MCMLXXXVIII. The longest so far has been 1888 with thirteen numerals – MDCCCLXXXVIII – and this number of digits will also be required for the years 2388 and 2788. It will not be exceeded until 2888 which will need fourteen characters – MMDCCCLXXXVIII.

The most recent years to require only one or two numerals were 1000 and 1500, being denoted by M and MD respectively. Next year, for the very last time, it will be possible to represent the date with just two characters – MM. After this, it will always be necessary to use at least three numerals.

Peter Macdonald
Harrow, Middlesex HA3 OSL

An early observation of noctilucent cloud?

From Dr M. Gadsden

Jonathan Shanklin, Director of the Comet Section, has drawn attention[1] to a pair of sketches in Charles Piazzi Smyth's notebooks. These have been reproduced in a recent book[2] by Olson & Pasachoff. Anthony Hopwood (private communication, 1998 November 29) had kindly sent me a copy of one of the illustrations and he wrote 'I was struck that the sky for the midnight observation on 12 July [1874] was virtually identical in brightness to that at 1030 on 15th July. This made me think of NLC!'

I went to the library at the Royal Observatory, Edinburgh, where Piazzi Smyth's notebooks are kept. Through the kind arrangement of Mary Brück and with the permission of the librarian, I spent some time going through them. In the original water colours,[3] it seemed to me that the clouds were neither shown structured (as noctilucent clouds so often are) nor silvery-blue in colour. The picture of 1874 July 15 seems to contain some thin, lit cloud for artistic effect or to remind himself that there were clouds high up in the sky. The picture from three nights earlier was of poor and worsening observing conditions: 'sky became obscured by fog at meridian passage'.

We may compare these sketches with Piazzi Smyth's observations of noctilucent clouds twelve years later[4] when he writes: 'On issuing, then, that night close upon twelve o'clock, from the Observatory computing room, upon the Calton Hill,... You might indeed have, at first sight, imagined that some great city, spread abroad over the plains of Fife was in a fierce state of extensive conflagration, so burning red was the first and lowest stratum extending along nearly 20° of the horizon. But that awful kind of redness passed quickly into lemon-yellow clouds in the stratum next above the red; and then came the silver-blue cloudlets just above the lemon- yellow, and even brighter still; but with an innocence of colour and gentleness of beauty, which at once exorcized the horrid idea of malignant flames devouring the works of man; and showed it must be something very different.'

Piazzi Smyth does not mention having seen the 'silver-blue cloudlets' before. I think he would have done had he seen them. Incidentally, after getting home he turned a spectroscope on the sky and was able to identify auroral light in the twilight. He confirmed that there was an auroral arc which 'passed across the Polar region at a considerable altitude, having the silver-blue cloudlets and their gorgeous red basement far below, but within, its wide-enclosing sweep'.

Michael Gadsden
Perth PH2 7HJ, Scotland

[1] Shanklin J. D., J. Brit. Astron. Assoc., 109(3) 156 (1999)
[2] Olson R. J. M. & Pasachoff J. M., Fire in the Sky, Cambridge University Press, 1998
[3] Piazzi Smyth C., Journal 26: 1873–74
[4] Piazzi Smyth C., Nature 34, 311–312 (1886)