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Today it is easy to take for granted that experiments can be conducted to improve our understanding and knowledge of the natural world around us, but in the first half of the seventeenth century this was not the case.

Natural philosophers (the term used to describe people that we know today as scientists) worked hard to demonstrate that verifiable, repeatable experiments were the best way to improve our collective knowledge of the natural world.

In the late-sixteenth and early-seventeenth centuries, many people believed that knowledge was acquired by looking for signs that were revealed by God through the movement of the planets, the weather, animals and plants. A person interested in increasing their knowledge would probably study the Bible, texts about knowledge accumulation such as Robert Recorde’s 'Pathway to Knowledge' and 'Castle of Knowledge', or literary epics such as Ovid’s 'Metamorphoses'. These were newly available in English, rather than Latin, thanks to the capability of the printing presses. In the universities of Europe most believed that conclusions could only be based on logical arguments made in the course of debate. Increasingly, however, some people such as Francis Bacon (1561-1626) and William Gilbert (c.1544-1603) began to champion practical experience and direct observation over the old method. 
 
For many historians of science, Gilbert is the ‘father of experimental science’ because in 1600 he provided the first systematic examination of magnets and their properties in his book 'De Magnete (Concerning the Magnet)'.  He was a firm believer in the Copernican heliocentric theory that the Earth and the other planets orbit the Sun at a time when many people still believed the Earth was the centre of the universe.  He claimed that the Earth was a giant magnet and used experiments with lodestones (natural magnets) to make his arguments.

Francis Bacon argued that experiments should not be based on a preconceived idea or hypothesis because that might lead people to skew experiments to fit their own ideas, rather than reveal truths about the natural world. The founding Fellows of the Royal Society adopted Bacon as their spiritual father when they outlined their aims and methods for working in Thomas Sprat’s 'History of the Royal Society' in 1667. Following the ideal that Bacon outlined in his writings, the Fellows aimed to conduct as many experiments as possible to see what would happen to specimens, animals and mechanical devices in different circumstances.

Neither Bacon nor Gilbert claimed to have invented this method of working, which clearly had its roots in older traditions such as medicine and natural magic (the name used to describe the comprehensive study of nature, distinguished from spiritual magic which involved the study of spirts and demons). They also did not provide a united front - Bacon was sceptical of Gilbert’s work for example - but the approach was soon taken up by natural philosophers including Fellows of the Royal Society. They redirected natural philosophy into a pursuit that we can recognise as science today.

New instruments

Image of hauksbee air pump, a wooden, brass and class instrument The Royal Society
Air pump by Francis Hauksbee, 1708.

Once natural philosophers gained an appetite for conducting experiments, they designed new instruments to create the different circumstances, or conditions, in which the specimen, animal or mechanical device was to be manipulated and observed.  In London, natural philosophers drew upon the skills of a range of makers to have their designs made into a reality. The construction of the air pump, for example, required glass blowers to make the glass vessels into which specimens, animals and mechanical devices were placed; clockmakers to make the intermeshing toothed wheels which operated the air pumps, and furniture makers or turners to make the wooden frames which supported the device.

This air pump was made by Francis Hauksbee the Elder (1660-1713). He used it in his role as Curator of Experiments at the Royal Society to demonstrate experiments at weekly meetings of the Fellows.

It is impossible to pinpoint exactly when the new approach became accepted by the majority of natural philosophers, but this had certainly taken place by the mid-late seventeenth century. To be accepted by others, experiments had to be repeatable and verifiable, which meant that the process had to be transparent and shared widely. In a process that is familiar from school lessons today, natural philosophers described the equipment they used in the experiment, the process undertaken and the variables that were measured. These step-by-step instructions, or logs, meant that anyone could repeat the experiment. If they did and reached the same result, the conclusions made were accepted to be true and trustworthy. If the experiment could not be successfully repeated the results were challenged.

Different instruments were needed to measure different variables. Natural philosophers in London drew on the skills of clock and watch-makers for timepieces to measure duration in the experiment, scale makers for balances to measure changes in mass, and barometer makers to measure changes in air pressure. Sometimes craftsmen’s skills overlapped, as with the barometer seen above, which was made by the clock and watchmaker Daniel Quare (1648-1724).

Francis Hauksbee

Image of original notes wrotten by Francis Hauksbee The Royal Society
'A description of a machine for giving a swift motion to bodies in vacuo without admitting ye external air’ by Francis Hauksbee

 

These notes were written by Francis Hauksbee and reveal the level of detail that natural philosophers went into when describing their experiments. Entitled

A description of a machine for giving a swift motion to bodies in vacuo without admitting ye external air.

Hauksbee describes the equipment used in his experiments with the air pump. In the experiment referred to, he wanted to be able to spin his specimens within the glass chamber of the air pump after the air had been removed. He wanted to maintain the vacuum that he had created and not allow air to get back into the chamber while he was spinning the specimen. He included an image of the device that he was going to use, which he labelled using letters. An itemised list on the next page tells us that for this device he made use of a ladder

such as is Generally used in Houses…, an iron bar that is secured to the ladder by two screws, an iron frame to hold the great wheel, a brass plate: …on which ye Recipient…is placed... and a winch: …which gives motion to ye whole….. 

Image showing the title page of Philisopical Transations, Royal Society

To be able to repeat Hauksbee’s experiments, readers needed to know exactly which equipment was used and how it was put together.

Experiment reports were shared through correspondence and publication. This gave people a way to observe experiments at a distance (whether that was in the UK or overseas) and approve, or contradict, their conclusions.

The 'Philosophical Transactions', seen here, was the first academic journal purely dedicated to natural philosophy and is still in publication today. Each issue contained descriptions of experiments conducted at the Royal Society, such as those by Hauksbee, and letters from correspondents living in Britain and abroad. 

Natural philosophers also published pamphlets and books based on their experimental work, as Gilbert had done previously. Robert Boyle’s (1627-91) work would appear familiar to a scientist today, even though the language he used appears old fashioned to a modern eye.  By way of example, Boyle began his fourth experiment, which explained how changes in air pressure affected an animal bladder in the air pump:

‘We took a Lamb’s Bladder Large, well dry’d … and leaving in it what half as much Air as it could contain’.  In this sentence, Boyle introduced the specimen and its pre-experiment condition. He continues: ‘This Bladder being convey’d into the Receiver, and the lever lifted on, the Pump was set awork’.  Here he explained his method step-by-step: ‘and after two or three executions of the ambient Air (whereby the spring of that which remain’d in the Glass was weaken’d) the Imprision’d Air began to swell in the Bladder’.  Here he described the results. By ‘spring of the air’,

Boyle meant air pressure, understood at this time to be like a coiled spring that exerted pressure. Mechanical analogies such as these helped natural philosophers to explain phenomena and results that had never been described before, and for which there were not always words to describe them. In this example, Boyle was showing his audience that the air contained within an animal bladder, which he used to represent the lungs of a living creature, was influenced by changes in air pressure in the surrounding environment. Its capacity was restricted as the pressure around it increased and was restored when the pressure was reduced. Experiments in this period were not all about making sweeping claims about nature and revolutionising knowledge - the vast majority were designed to observe what would happen in different scenarios.

Trust and distrust

While the majority of natural philosophers accepted these activities and the results they generated, because of the quality checks mentioned above, not everyone did. There were examples in the period of people that were not convinced, such as Margaret Cavendish, who was the first woman to visit the Royal Society (the first female Fellow, Kathleen Lonsdale, was not elected until 1945). Cavendish was critical of the Fellows’ reliance on new optical instruments such as the microscope and telescope, suggesting that their eyes were being deceived by the lenses.  Her remarks, which were repeated by others, demonstrate that it took several years for new instruments to become trusted by some people. She also wrote many books, one of which was entitled 'The Description of a New World, Called the Blazing-world', in which she openly satirised the Society and warned of a dystopian future for natural philosophy.   

Cavendish was not alone in her use of satire directed at the Royal Society, and natural philosophers in general. In the late 1670s Thomas Shadwell’s play, 'The Virtuoso', attracted audiences in London to its story involving the character Sir Nicholas Gimcrack, a natural philosopher who conducts lots of different amusing experiments. Robert Hooke recorded visiting the play in his diary and being outraged that the character seemed to be based on him. Satirical critiques of experiments continued throughout the eighteenth and nineteenth centuries and reveal one view of natural philosophers beyond their own circles. However the monarchy, the government and the majority of the wealthy elite were keen supporters of natural philosophers’ work and could see how new knowledge could be put to use.

New science and new networks

While it is impossible to sum up the many varied ways by which science is carried out today as one single simple method, the concept of the experiment as a way of improving our collective knowledge of the natural world is a crucial part of scientific practice and has its roots in the seventeenth century. Thanks to hubs such as the Royal Society and publications such as 'The Philosophical Transactions', natural philosophers throughout Europe were part of a network. They may not have always got along on a personal level and they may sometimes have had disagreements, but they realised that the network was essential for getting their ideas accepted by others, as it still is today.