Bacon's Study in The Stripling Thames by Fred Thacker
1910: Bacon's Folly in Thames Valley Villages by Charles G Harper

Roger Bacon was an eleventh century Franciscan Friar who lived in Oxford.
1292: Roger Bacon died

Do not walk too near the Friar's Tower!

It was said that Roger Bacon had so magically arranged his tower that if there was anyone cleverer than he in Oxford they would be killed by the tower collapsing on them. It was thus ironically said to all new undergraduates.

In the Antient and Present State of the City of Oxford, 1773 -

Before I go farther, I must take Notice of the Tower, with a Gate and common Passage underneath, called Friar Bacon's Study, which standeth on this Bridge near the End next the City.
A Name merely traditional, and not in any Record to be found. It has been delivered as a Fact from one Generation to another, and from them well versed in Astronomy and the Antiquites of Roger Bacon, a Franciscan Friar of this Place, who died 1292, known to be a great Astronomer, that he was used in the Night to ascend this Place, and to take the Altitude and Distance of the Stars.
Of its Foundation, it is most reasonably supposed to have been built in King Stephen's Time, or in the Beginning of the troublesome Wars of the Barons, being then built as a Pharos or high Watch Tower for the Defence of the City.
In the 28th year of King Henry III. and King Edward] 1st's Reigns there are mentions of it under the Name of Nova Porta & Turris supra Pontem Australem. New Gate and the Tower on South Bridge; not that it was then newly built, but it was the Name imposed on it and by that Name called through all the Reigns till Queen Elizabeth 1st.
In the 7th Year of this Queen, it was let to Dr. White, for several Years conditionally, that he should suffer the Archdeacons Court of Berks to be kept there, and also that the Citizens should have free Ingress and Regress in Times of Need or Danger, for the Defence of the City.
But in the 33rd year of Queen Elizabeth 1st it was let to the Citizens by the Name of Batchelor's Tower so called by Mr. Windfore.

1668: Samuel Pepys his diary -

So to Friar Bacon's study: I up and saw it, and gave the man a shilling. Oxford mighty fine place.

1779: Bacon's Tower demolished

1780? Michael Angelo Rooker (1746-1801) painted Folly Bridge & Bacon's Tower (Worcester College):

Folly Bridge & Bacon's Tower, Michael Angelo Rooker, 1780
Folly Bridge & Bacon's Tower, Michael Angelo Rooker, 1780?

An engraving by James Basire of that painting by Michael Angelo Rooker appeared in the Oxford Almanack of 1780. The Ashmolean have a copy. And here is a photo (taken through glass) of a private copy -

Folly Bridge & Bacon's Tower, James Basire's engraving, picture by Michael Angelo Rooker, 1780
Folly Bridge & Bacon's Tower, James Basire's engraving, picture by Michael Angelo Rooker, 1780
Note that the passenger is stepping aboard the punt rather more convincingly!
JMW Turner's copy below also has this feature.

1785: Friar Bacon's Tower, S Hooper -

Folly Bridge & Bacon's Tower, S Hooper, 1785
Folly Bridge and Bacon's Tower, 1785, S Hooper

1787: Bacon's Tower, J M W Turner (making a copy of Rooker's picture [see above] ) -

Folly Bridge & Bacon's Tower,Turner 1787
Folly Bridge and Bacon's Tower, 1787, JMW Turner.

The boatman is punting the ferry for three undergraduates.

1837: Memorials of Oxford by James Ingram -

... Roger Bacon ... made many astronomical observations on the tower of Sunningwell church, about four miles south of Oxford. This, however, though not far distant, was sometimes of difficult access, especially in winter : the meadows on that side of Oxford are now frequently overflowed, but they were then one continued swamp, so that Grandpont, where the Thames is crossed on the road to Abingdon, extended to a long causey of forty arches. On the part, in which it abuts on the south bank of the river, there was an archway with a tower over it, which was not pulled down till 1779, and had acquired from his use of it the name of Friar Bacon's study. The Franciscan convent, of which he was a member, was in a part of the parish of St. Aldate's, which is still called the Friars, and was conveniently situated for this station, which is the earliest observatory in Oxford of which there is any record.

Bacon's Tower 1859
Bacon's Study in Memorials of Oxford by James Ingram, 1837

Bacon's Tower, Mr & Mrs Hall -

Bacon's Tower 1859
Mr & Mrs Hall published this wood cut of Bacon's Tower in 1859.

And look at the height of the water coming over that overshot wheel. I cannot see it as less than twelve feet. I don't believe it! It must have been an undershot wheel which the artist has misunderstood.

1862: S.H.Grimm made this drawing, copied by J E Vincent in 1909 -

Bacon's Tower 1862
Friar Bacon's Study, S H Grimm, 1862, copied by J E Vincent, 1909

There is still a fairly weird and wonderful building on the island, 5, Folly Bridge. In 1911 this became the home of Robert Gunther, science historian. An unusual castellated house embellished with statues and cast iron balconies on the outside. This was not Bacon's Tower - but was no doubt a tribute to it.

On Folly Bridge 2006

Bacon's Tower was the home of the great Roger Bacon, Franciscan monk and scholar, astronomer, mathematician etc in the middle ages.
(Not to be confused with any of the Francis Bacons)

He did sometimes use in the night season to ascend this place, [his study on what is now Folly Bridge] on an eyot midstream in the Thames environed with waters, and there to take the altitude and distance of stars and make use of it for his own convenience...

His estimate of the distance of the stars was 131,000,000 miles. Which is sufficiently close to the actual distance of the sun as to make one wonder how he did it.
He was accused of practising magic - and it is just possible that this is the origin of all the "wizard in the tower" tales. Professor Tolkien would have known this story. You could say Bacon's Tower is the original for Isengard! "Isis-guard" ? - the tower on the Isis?
J R R Tolkien (about Oxford) -

From the many-willow'd margin of the immemorial Thames,
Standing in a vale outcarven in a world-forgotten day,
There is dimly seen uprising through the greenly veiled stems,
Many-mansion'd, tower-crowned in its dreamy robe of grey,
All the city by the fording: aged in the lives of men,
Proudly wrapt in mystic mem'ry overpassing human ken.

Roger Bacon wrote about Peregrinus -

He gains knowledge of matters of nature, medicine, and alchemy through experiment, and all that is in the heaven and in the earth beneath. ...
Moreover, he has considered the experiments and the fortune-telling of the old witches, and their spells and those of all magicians. And so too the illusions and wiles of all conjurors; and this so that nothing may escape him which ought to be known, and that he may perceive how far to reprove all that is false and magical.

But he himself then went on into what we must regard as scientific investigations. He had an extraordinarily fertile mind.

Bacon's Telescope:
For we can so shape transparent bodies, and arrange them in such a way with respect to our sight and objects of vision, that the rays will be reflected and bent in any direction we desire, and under any angle we wish, we may see the object near or at a distance ... So we might also cause the Sun, Moon and stars in appearance to descend here below...
Bacon's Boats with engines:
It is possible to make Engines to sail withall, as that either fresh or salt water vessels may be guided by the help of one man, and made sail with a greater swiftness, than others will which are full of men to help them.
Bacon's Car:
It is possible to make a Chariot move with an inestimable swiftnesse - and this motion to be without the help of any living creature.
Bacon's Aeroplane:
It is possible to make Engines for flying, a man sitting in the midst whereof, by turning onely about an Instrument, which moves artificiall Wings made to beat the Aire, much after the fashion of a Bird's flight.
Bacon's Diving Suit:
A man may make an Engine, whereby without any corporal danger, he may walk in the bottome of the Sea, or other water.

Roger Bacon said -

A little learning is a dangerous thing - but none at all is fatal.
Et harum scientiarum porta et clavis est Mathematica.
Mathematics is the door and key to the sciences.
Neglect of mathematics works injury to all knowledge, since he who is ignorant of it cannot know the other sciences or the things of the world.
Prudens quaestio dimidium scientiae.
Half of science is asking the right questions.
For the things of this world cannot be made known without a knowledge of mathematics. For this is an assured fact in regard to celestial things, since two important sciences of mathematics treat of them, namely theoretical astronomy and practical astronomy. The first ... gives us definite information as to the number of the heavens and of the stars, whose size can be comprehended by means of instruments, and the shapes of all and their magnitudes and distances from the earth, and the thicknesses and number, and greatness and smallness, ... It likewise treats of the size and shape of the habitable earth ... All this information is secured by means of instruments suitable for these purposes, and by tables and by canons .. For everything works through innate forces shown by lines, angles and figures.

And he was born in the year 1214 !
It will come as no surprise that his contemporaries did not understand him - and he suffered considerably for his studies. But his memory still endures. It might even be almost everything we know as "science" owes it existence to him (or through him) - so without him many of us might be dead - on the other hand ...

Roger Bacon

The Great Philosopher
Known as the Wonderful Doctor,
Who by the Experimental Method,
Extended marvellously the realm of science.
After a long life of untiring activity,
Near this place
In the home of the Franciscan brethren,
Fell asleep in Christ,
A D 1292

In 1907 there was a University Pageant at which there was a recreation of the story that Roger Bacon demonstrated a Brazen Head which was said to talk and reply to questions. Quite what this was nobody knows - maybe Alexander Graham Bell was 600 years late in his invention? -

Friar Bacon demonstrates the brazen speaking head, 1270, (photo 1907)
Friar Bacon demonstrates the brazen speaking head, 1270, (photo 1907)

Probably more than you wish to know about Friar Bacon

1909: Fred S Thacker, The Stripling Thames -

Astride the Norman bridge once stood a tower known as Friar Bacon's Study, which tradition says the old astronomer used as an observatory of the stars. It was built, probably, at the end of the twelth or early thirteenth century.
Somewhere about 1650, having fallen very ruinous, it was leased to a citizen named Welcome, who repaired and heightened it. His neighbours, sceptical of its advantage to him, nicknamed his venture "Welcome's Folly", and the epithet stuck ousting high-sounding "Grand Pont" and legitimate "South Bridge"; and thus we get the modern colloquial title ["Folly Bridge"].

Samuel Ireland in 1791, quoted in the Folly Bridge section, casts doubt on this story - but my money's on Fred!
Fred Thacker quotes a nice story about Roger Bacon, from Wood -

Once upon a time several Scholars of Cambridge came to dispute with the Scholars of Oxford, the which Fryer Bacon hearing, fained himself a Thatcher, and when he was upon a house at Oxford Town's end, he upon the approach of the Cantabrigians, came down to meet them, and drawing near to them, one of the Cantabrigians said to him:
Rustice quid quaeris?
Bacon the Thatcher answered:
Ut mecum versificeris.
Then quoth another of the Cambridge Scholars:
Versificator tu ?
Bacon answered
Melius non Solis ab ortu.
Whereupon the Cantabrigians seeing that Oxford Thatchers were so good Scholars themselves, returned to Cambridge re infecta.

It was of course perfectly understandable that Oxford Scholars should have been nervous of meeting with the true scholarship of Cambridge and thus resorted to trickery to gain the day.
(I speak as a Cambridge man)