Ada Lovelace and her contribution to computer science

Ada Lovelace (1815-1852) is known as the first computer programmer. What did she really contribute to computing? So many blog posts, articles and books get bogged down describing her childhood, and her famous father and overbearing mother. But what did she actually do?

A while ago I got stuck in and actually read the paper she actually wrote.  "Sketch of the Analytical Engine invented by Charles Babbage... with notes by the translator. Translated by Ada Lovelace"

In fact, she translated into English a paper by an Italian engineer, Luigi Menabrea, and clearly felt that his description did not go far enough, because she added her own notes at the end, which amount to more detail than the original translation.

The original paper by Menabrea was supposed to sell the idea of the Analytical Engine, a machine designed by Charles Babbage but not yet constructed. Money needed to be raised for this endeavour. Menabrea explains what the machine can do. To some extent he does try also to sell the idea, but his writing can be quite dry: 'To give an idea of this rapidity, we need only mention that Mr. Babbage believes he can, by his engine, form the product of two numbers, each containing twenty figures, in three minutes.'

Lovelace wanted to add more, and her writing is glowing with excitement about the machine. She added 7 detailed discussion notes, labelled A to G, and also 20 numbered footnotes. In the numbered footnotes she comments on issues with the translation. She also comments sometimes on how she feels that Menabrea hasn't quite understood completely the novelty and potential (for example 'M. Menabrea's opportunities were by no means such as could be adequate to afford him information on a point like this'). In the notes labelled A to G she explains many of the concepts that are the fundamentals of computing today.

Note A

This note spells out that the Analytical Engine is a general purpose computer. It doesn't just calculate fixed results, it analyses. It can be programmed. It's flexible. It links 'the operations of matter and the abstract mental processes of the most abstract branch of mathematical science'. This is not just a Difference Engine, but instead offers far more. She is very clear that 'the Analytical Engine does not occupy common ground with mere "calculating machines". It holds a position wholly its own'. It's also not just for calculations on numbers, but could operate on other values too. It might for instance compose elaborate pieces of music. 'The Analytical Engine is an embodying of the science of operations'. Lovelace has a beautiful turn of phrase that evokes her delight in imagining where this could go: it 'weaves algebraic patterns just as the Jacquard loom weaves flowers and leaves'.

Note B

This note is about memory, the 'storehouse' of the Engine. It is about variables, and retaining values in memory. She describes how the machine can retain separately and permanently any intermediate results, and then supply these intermediate results as inputs to further calculations. Any particular function that is to be calculated is described by its variables and its operators, and this gives the machine its generality.

Note C

This note is about reuse: the Engine uses input cards, as used in the Jacquard looms. Lovelace had toured the factories of the north with her mother and seen the Jacquard looms in action. They would have been the cutting edge of technology at the time. Intricate patterns were woven by machines, with thousands of fine threads, all controlled by punched cards. The cards needed to be created by card punching machines, with detailed tables of numbers that would be translated into the patterns of holes. The cards allowed a design to be repeated, and they were bound together in a sequence. She explains that these input cards, can be reused 'any number of times successively in the solution of one problem'. And furthermore, that this applies to just one card, or a whole set of cards. The train of cards can be rewound until they are in the correct position to be used again.

Jacquard loom, Nottingham Industrial Museum

Punched cards used in Jacquard loom, Nottingham Industrial Museum

 

Note D

This note is about the order and efficiency of operations. She explains that there are input variables, intermediate variables, and final results. Every operation must have two variables 'brought into action' as inputs and one variable to use as the result. We can then trace back and inspect a calculation to see how a result was obtained. We can see how often a value was used. We can think about how to batch up operations to make them more efficient. She begins to imagine not just how the machine will operate, but how programmers will have to think carefully about their programs, how they will debug them and how they will optimise the algorithms they implement.

Note E

In this note Lovelace explains how loops or 'cycles' can be used to solve series, for example to sum trigonometrical series. With a worked example (used in astronomical calculations), she abstracts out the operations needed to produce terms in the series and works on a notation for expressing cycles that include cycles. Note 18 expands further to explain that one loop can follow another, and there may be infinitely many loops.

Note F

This note begins with the statement 'There is in existence a beautiful woven portrait of Jacquard, in the fabrication of which 24,000 cards were required.' Babbage was so taken with this woven portrait that he bought one of the few copies produced. The amount of work that machines could do, unfailingly, without tiring, was changing the face of industry. The industrial revolution was sweeping through the country. Lovelace explains how the Engine will be able to solve long and intensive with a minimum of cards (they can be rewound, and used in cycles). The machine can calculate a long series of results without making mistakes, solving problems 'which human brains find it difficult or impossible to work out unerringly'. It might even be set to work to solve as yet unsolved and arbitrary problems. 'We might even invent laws for series or formulae in an arbitrary manner, and set the engine to work upon them and thus deduce numerical results which we might not otherwise have thought of obtaining; but this would hardly perhaps in any instance be productive of any great practical utility, or calculated to rank higher than as a philosophical amusement.'
 

Note G 

She concludes with the scope and limitations of the Analytical Engine. She is keen to stress the machine's limitations and about using the machine for discovery: it doesn't create anything. It has 'no pretensions to originate anything'. Lovelace then enumerates what it can do, but warns against overhyping it. Alan Turing references her concerns in his 1950 paper Computing Machinery and Intelligence (which is also well worth a read). In this paper he discusses 9 objections that people may raise against the possibility of AI. One of these 9 objections is Lady Lovelace's Objection. He writes:

Our most detailed information of Babbage's Analytical Engine comes from a memoir by Lady Lovelace (1842). In it she states, "The Analytical Engine has no pretensions to originate anything. It can do whatever we know how to order it to perform" (her italics).

In Note G we also get the detailed trace of a substantial program to calculate the Bernoulli numbers, showing the order of operations combining variables to make results. The trace shows looping and storage, showing intermediate results, and the correspondence with the mathematical formulae being calculated at each step. She inspects the program for efficiency, working out the number of punched cards required, the number of variables needed and the numbers of execution steps.

Lovelace wonders, in the third paragraph of this Note, whether our minds are able to follow the analysis of the execution of the machine. Will we really be able to understand computers and their abilities? 'No reply, entirely satisfactory to all minds, can be given to this query, excepting the actual existence of the engine, and actual experience of its practical results.'

Ada Lovelace is buried in Hucknall Church, Nottingham. She died aged 36, and never got to see the Analytical Engine constructed.

Storm damage in Aberystwyth in January 2014 and in January 1890

An unusually high tide in Aberystwyth in January 2014 has severely damaged the promenade. We do get some spectacular weather here on the west coast of Wales.

Broken railings and paving on Aberystwyth promenade.

Forceful storms that broke up the promenade also occurred in other years, particularly in 1927 and 1938, and their aftermath was photographed and looks remarkably similar. In January 1890, the Cambrian News reported a storm at Aberystwyth which caused trouble to the train travelling between Aberystwyth and Machynlleth.

"The uptrain from Aberystwyth had to wait in the Junction for over half an hour until the tide had partially subsided. Then the line was cleared of pieces of timber and accumulations of grass and rushes and the train proceeded, though the water was half way up the wheels."

Would the Junction that was referred to here be Dyfi Junction station? The storm in 1890 also caused a hole in the sea wall, in a very similar location to the one that's been opened up this year:

"Unfortunately, the masonry forming the slipway near the Queen's Hotel gave way and subsequently a large hole was washed in the sea wall"

The Queen's Hotel is no longer a hotel, but still exists as a building. It has been used for many purposes since 1890, and has most recently been used as council offices and archives. It's currently up for sale, at a price of approximately £1 million.

The hole in the sea wall caused by this year's weather shows just how powerful the sea is against our buildings and defences.

And in 1890 a steamer in distress was spotted out in the bay, carrying a cargo of pig-iron but having lost its funnel in the storm. The lifeboat was launched, under the command of a Mr Tom Williams, and the crew were rescued and taken to the Belle Vue Hotel for "much-needed refreshments". Our lifeboat was also out rescuing in 2014 and, so far, everyone's safe and sound.

Waves wash over the promenade in front of Alexandra Hall and flood the ground floor.

More photos of what happened in 2014 are on Flickr.

Alfred Henry Allen, an extraordinary chemist

My parents have just written a fantastic paper about A. H. Allen, Sheffield's first Public Analyst. Alfred Henry Allen lived from 1846 to 1904, in a time of gas lamps, horse drawn carriages and dubious Victorian era water quality. His chemical investigations and new methods of analysis shone a light on the practices of careless or unscrupulous food and drink manufacturers.

The paper describes lots of his achievements. For example he investigated why the drinking water in some areas of Sheffield contained harmful lead, which was poisoning the population, while other areas had lead-free water (it turns out that the leaded water came from reservoirs which were found to be acidic, and the acid dissolved some of the lead from pipework, so he proposed that the water be treated with lime and limestone to remove the acidity).

Allen investigated the proportions and effects of the different alcohols found in whisky, and even did some testing on himself, drinking a wine glass full of whisky every evening for 3 weeks in order to show that amyl alcohols did no harm. You'll also want to read about his concerns about the "slovenly and ignorant" production of cider, where the cider makers reused manure carts to carry apples.

He didn't just do the science, but also communicated it to a wider audience. He gave public talks and "entertainments", such as Alchemy and the Alchemist, Chemistry of Explosives, Visible Sound, and Artificial Light. The paper points out that "People in Victorian times had a thirst for entertainment of a scientific and paranormal nature", and I imagine his lectures would have been very popular. Would his talk on Chemistry of Explosives have featured exciting demonstrations that would be impossible today for health and safety reasons? What magic would the lecture on Alchemy have shown?

Allen published over 150 papers and many books on methods of chemical analysis. He wrote 13 volumes of a book called "Commercial Organic Analysis", which needed continual updating as science progressed. He was a founder member of the Society of Public Analysts. He died of diabetes, a disease that had no cure or effective treatment at the time (though Allen had published papers, a book and chemical analysis methods for the determination of sugars in urine, so he would have been well able to measure his condition). During his life, he developed a business of consulting chemists (A.H. Allen & Partners), at which, after many years, my parents worked, and they have now honoured him by documenting his place in history.