Today marks 80 years since the end of the Battle of Britain, in which radar played a critical role for the first time. Let's also recall that British radar development stemmed from an Air Ministry prize of £1000 to anyone who could build a ray that could kill a sheep at 100 yards
The idea of a "death ray" was not new, but the Ministry was alarmed in the mid-1930s by reports that the Germans were ahead in death ray development
The physicist Robert Watson-Watt was asked to investigate these reports. He turned the problem over to his assistant Arnold Watkins, who quickly demonstrated the theory was impossible, but also that the principle might be used to detect aircraft at a distance
Watson-Watt and Watkins worked quickly and within a matter of months built a prototype set that was used to detect a Handley-Page Heyford bomber at 7 miles Image
The transmitter used was simply an existing BBC shortwave radio broadcast station. They set their recievers up and detected the radio broadcasts echoing back off the target
Watkins made the inspired suggestion as he had been investigating commercial radio sets, and a model from the General Post Office mentioned in the user manual that end users could expect interference if aircraft were flying overhead
Watkins and Watson-Watt are credited with the British invention of radar and this first success test against an aircraft. A number of nations at this time were making independent leaps and bounds in "radar" so there's no single inventor credited
The "Chain Home" radar network was built in great secrecy and at great speed. Technically it was relatively simple but this diagram shows just how wide the coverage was in 1939 then 1940 Image
So the moral of the story is don't try and kill sheep, don't believe the hype, and always read the instruction manual
Watson-Watt was also the father of "High Frequency Direction Finding" (or Huffduff), which he had first come up with to try and track lightning strikes.
HF/DF allowed radio transmissions to be accurately located and when miniaturised into a shipborne version was instrumental (alongside more advanced radar) in helping win the "Battle of the Atlantic"
The beauty of HF/DF is that it's totally passive - you don't need to transmit a signal yourself and therefore potentially give away your presence - and also that you don't need to know what's being transmitted so cryptanalysis is not required.
You basically just get a dial that says "there be dragons" and can guess from the characteristics of the signal an approximate range and even if the transmitting antenna is wet or not (i.e. is it a freshly surfaced submarine) Image
It was the work of an exiled Polish engineer, Wacław Struszyński, which made a miniaturised and accurate shipborne set possible. Previously the system used land-based receivers on a baseline of hundreds of miles form eachother. Image
Struszyński's development of a miniaturised antennae, and also a method to cancel out the disruption caused by the ships own superstructure is described as "a breakthrough of transcendent importance".
The German U-boat system was so terribly effective because it was centrally controlled. Central control relied on communications, which were by radio. Such was the confidence that accurate radio direction finding at sea was impossible that they never changed this
The Germans had plenty of photos of the HF/DF antennae on allied ships, they knew that allied ships and aircraft could quite reliably and conveniently find themselves in the right place at the right time, they just did not believe this could be down to passive direction finding Image
It is estimated that "without shipborne high frequency direction finding, Allied convoy losses in early 1943 would have been 25 to 50 percent higher, with U-boat kills being reduced by one-third"
Footnote and an apology. I spent most of that threat calling Arnold Wilkins "Arnold Watkins". Image

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More from @cocteautriplets

May 11
The derailment by strikers of the Flying Scotsman on May 10th 1926 has meant a much more serious and fatal rail accident in Edinburgh later that same day which claimed 3 lives and injured many has been somewhat overlooked 🧵👇🚂
The 1:06PM train from Berwick-upon-Tweed to Edinburgh hit a goods train being shunted across its path at St. Margaret's Depot just west of the tunnel under London Road. Due to the General Strike, most signal boxes were unmanned and only a rudimentary signalling system was running
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Apr 30
It's been hard to find time recently for any in-depth threading, but I think tonight we can sneak in the story of the lesser-known Leith shipyard of Ramage & Ferguson, builders of luxury steam mega-yachts to the Victorian and Edwardian elites. ⛵️🧵👇 The modelmakers loft at Ramage & Ferguson, 1906. © Edinburgh City Libraries
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Apr 7
As promised / threatened, there now follows a thread about the origins and abolition of the Tawse as the instrument of discipline in Scottish teaching. So lets start off with the Tawse - what is it and how did it evolve? 🧵👇
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Jan 24
This pub has been in the news for the wrong reasons recently, but despite appearances it's a very important pub; a surviving example of only a handful of such interwar hostelries built in #Edinburgh - the Roadhouse. And these 9 pubs have a story to tell. Shall we unravel it?🧵👇 The Anchor Inn, West Granton Road.
The short version of the Roadhouse story is thus: a blend of 1930s architecture and glamour used by the licensed trade to attract a new generation of sophisticated, Holywood-inspired, car-driving drinkers. That's partly true, but not the full story here 1934 Dunlop Tyres advert showing cars arriving at an Art Deco Roadhouse. © Illustrated London News
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Jan 18
In 1839, Dr. Thomas Smith of 21 Duke (now Dublin) Street in #Edinburgh tried on himself a purified extract of "Indian Hemp" - Cannabis sativa. He "gave an interesting account of its physiological action!". He was most probably the first person in Scotland to get high. Dr Thomas Smith of T. & H. Smith. 1807-1893
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Dec 29, 2023
Between 1950 and 1973, #Edinburgh built 77 municipal, multi-storey housing blocks (of 7 storeys or more), containing 6,084 flats across 968 storeys. So as promised, I've gone and made a spreadsheet inventory of them all. Let's have a look at them chronologically 🧵👇 Screenshot - spreadsheet of Edinburgh's multi-storey municipal housing blocks.
1950-51 saw the first such building - the 8 storey Westfield Court with 88 flats (and a nursery on the roof!) Built by local builders Hepburn Bros, it was heavily inspired by London's Kensal House by Maxwell Fry. It was a bit of a 1-off though and is rather unique in the city. Westfield Court
There then followed a series of experimental mid-rise blocks, variations on a theme, as a rather conservative local administration (headed by the Progressive Party) tried to work out what it wanted to do regards high-rise housing post-war.
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