L.J. Comrie

Biography

Paragraphs in quotes are drawn from Frank da Cruz's web page on L.J. Comrie at www.columbia.edu/acis/history/comrie.html
Remaining text is drawn from Garry Tee's University of Auckland Comrie Lecture in 2000 

"Leslie J. Comrie, Ph.D, (1893-1950): English astronomer and pioneer in mechanical computation, was born in Pukekohe, New Zealand, and educated at Auckland University College, University College London, and Cambridge University. Like his American contemporary, Columbia University Astronomy Professor Wallace Eckert, Comrie was a pioneer in the application of punched-card machinery to astronomical calculations and the production of astronomical tables: the first scientific use of these machines, which had been designed purely for business use."

As an undergraduate he founded the Auckland University College Astronomical Society, now called the Comrie Astronomical Society, which sponsors the annual Comrie Lecture. Despite severe deafness he insisted upon joining the New Zealand Expeditionary Force, and he was severely wounded in France. He then studied at University College London and Cambridge University, and from 1923 to 1925 he pioneered the teaching of numerical analysis in the USA, at Swarthmore College and at Northwestern University.

Click here to hear Dr. Comrie’s interview "Mathematics in war" on radio station 1YA on April 5, 1948

On 1924 December 31 at the meeting of the American Astronomical Society in Washington D.C; Comrie gave a detailed survey of mathematical tables and calculating machines used in astronomical computation. He concluded that multiplication and division could then be done with calculating machines more conveniently than with logarithm tables, and he announced his intention to abolish logarithms for calculation. In 1948, on his only return visit to New Zealand, he explained with justifiable pride that he had succeeded, since serious scientific computing no longer used logarithms.

At the Nautical Almanac Office at Greenwich from 1925 to 1936, Comrie invented the first computing laboratory, and he revolutioned the computation of the Nautical Almanac by calculating machines. In 1938 he founded in London the Scientific Computing Sevice. That was the first computing consultancy firm, and it had immense influence upon the development of computing. He employed many women as professional computers, teaching them how to use a wide range of calculating machines to perform various types of scientific computation. The many mathematical tables published by Comrie were acclaimed as the finest tables ever produced.

Creating the computer

"Comrie was the first to turn punched-card equipment to the computation of astronomical tables by the method of finite differences, as envisioned by Babbage 100 years earlier for his Difference Engine, but not practical until the appearance of reliable calculating machines. Differencing was used because the early punched-card machines capable only of addition and subtraction; not division, multiplication, exponentiation, roots, trigonometric functions, etc. Comrie had already been using this method for many years with hand-operated desktop calculators. (An excellent review and history of differencing and its application to various types of calculating machines is given in Comrie's 1928 Brusviga-Dupla article (publication list below))."

"Comrie's April, 1928, article On the Construction of Tables by Interpolation describes at length a laborious and error-prone procedure for interpolating numeric table values by desktop calculator and then, in the last few pages, describes how to do the same thing using punched cards, a tabulating machine, a duplicating punch, and a sorter with far greater speed, but then goes on to conclude that since Hollerith equipment is so expensive, it is rarely practical -- as is often the case with new technology."

The beginnings of ‘programming’

"In his May, 1932, article, The Application of the Hollerith Tabulating Machine to Brown's Tables of the Moon, Comrie describes his punched-card methods in far greater detail, with paragraphs given over the function and operation of each component -- card, punch, sorter, tabulator, printer -- plus plates showing each. In this article, for the first time, we have a description of "programming":

“Automatic Control.—This feature is of the utmost importance in the present application. When the cards corresponding to any one date have been added, the feeding must cease while the total is being printed, the counters must be cleared and then the feeding must be resumed. This sequence is performed automatically, without any attention whatsoever on the part of the operator.”

(Comrie goes on to describe how the tabulator plugboard has been wired to "compare" a key field on a pair of cards and handle the sums and reset the counters when they differ.)

“A Hollerith installation was used in H.M. Nautical Almanac Office in 1929; actually punching was started six months before the arrival of the sorter and tabulator, as it was necessary to punch 20,000,000 holes in half a million cards. ... The sorter and tabulator, which may only be hired, cost about £2 a day. The cost of doing by hand what was done on the machines has been estimated at £6000; this estimate probably errs on the low side. The cost with the machines was certainly less than £1500.”

"Thus in the four years since his 1928 article, punched-card computation had become cost effective. In the following years (as can be seen from his publication list, below) Comrie became strong advocate of the punched-card method. Like Eckert, he was preoccupied with saving steps, particularly error-prone and time-consuming ones like copying the results of one calculation to the input of the next. Comrie was also a strong proponent of using standard, "off-the-shelf", unmodified hardware (calculators or punched-card equipment), rather than modified, one-of-a-kind, or special-purpose machines because he wanted the methods he developed to be useful to others. Eckert, on the other hand, was constantly prodding IBM to modify their designs and to produce special one-off machines for his lab, and IBM was happy to comply. Comrie expressed his feelings in 1946: “ I have sometimes felt that physicists and engineers are too prone to ask themselves "What physical, mechanical or electrical analogue can I find to the equation I have to solve?" and rush to the drawing board and lathe before enquiring whether any of the many machines that can be purchased over the counter will not do the job. ... [L]ook at what has been provided by and for the industry before you leap to the adventure of a special design.”

Comrie was elected Fellow of the Royal Society shortly before his death in 1950. A lunar crater (23.3N 112.7W) and an asteroid bear Comrie's name.

Further reading

1. Croarken, M.J., "L.J. Comrie and the origins of the Scientific Computing Service", IEEE Annals of the History of Computing, Vol.21 No.4 (1999), pp.70-71.

2. Croarken, M.J., "L.J. Comrie, A forgetten figure in the history of numerical calculation", Mathematics Today, Vol.36 No.4 (Aug 2001), pp.114-118.

3. Croarken, Mary, "Computing in Britain During World War II", IEEE History of Technology Summer Meeting (6 July 2002).

4. Grier, David Alan, "The Human Computer and the Birth of the Information Age", Philosophical Society of Washington: Joseph Henry Lecture (11 May 2001).

5. Grosch, Herbert R.J., Computer: Bit Slices from a Life, Third Edition, 2003 (in manuscript). First edition published by Third Millenium Books, Novato CA (1991).

6. Sadler, D. H., "Comrie, Leslie John", in Gillespie, Charles Couston (Ed.) Dictionary of Scientific Biography, Charles Scribner's Sons, NY (1970-80).

7. Wilkes, Maurice, "Babbage's Expectations for his Engines", IEEE Annals of the History of Computing, Vol.13 (1991), pp.141-145.

(Sources: Columbia University website http://www.columbia.edu/acis/history/comrie.html and University of Auckland Comrie Lecture 2000 by Garry Tee)