Category Archives: Talks

Chess — Dr Phil Judkins — 20th Sept 2021

In a ref­er­ence to the often com­plic­ated tac­tics involved, cycle racing has been described as ‘chess on wheels’.   So it was per­haps appro­pri­ate that Dr Phil Judkins’ present­a­tion on  tech­no­lo­gical devel­op­ments in air war­fare during WWII should include an illus­tra­tion of a rather Heath Robinson adapt­a­tion of an upturned bicycle used to rotate a radar aerial through the required 360 degrees.

We wel­comed back Dr Judkins, who had spoken to us only seven weeks earlier and who kindly agreed to stand in at short notice when our sched­uled speaker became ill. Phil’s latest talk, Chess — Europe’s ‘Wizard War’ in the Air, to give it its full title, was a follow-up to his equally fas­cin­at­ing present­a­tion on the Atlantic ship­ping con­voys.

Phil is an inter­na­tion­ally acknow­ledged  expert on the his­tory of radar, radio inter­cep­tion and elec­tronic war­fare. Retiring from a suc­cess­ful busi­ness career, he gained a PhD in the his­tory of radar from Cranfield University, taught the MA in the History of Military Intelligence at the University of Buckingham and cur­rently researches inter­war elec­tron­ics as a Visiting Fellow at the University of Leeds. He chairs the Defence Electronics History Society.

An RAF nav­ig­ator oper­ates an H2S radar dis­play. © Crown Copyright

Phil gave us a hint of what was to come when he told us: “I’d like to recount the story about the air war which you don’t usu­ally hear — the moves in the deadly chess game between German and British sci­ent­ists, and between British and German air com­mand­ers, fought out for six years in the night skies over Europe, where all the chess moves decided who would live and who would die.”

It was chilling stuff. As Phil added, neither side had all the good ideas and neither side made all the mis­takes. But Britain, he poin­ted out, had a strange defin­i­tion of the word ‘secret.’ Tight secrecy sur­roun­ded radar devel­op­ment, and man­u­fac­tur­ers were rig­or­ously checked for for­eign con­nec­tions — or so we were told.

Prior to 1939 the annu­ally pub­lished RAF List con­tained the address and all staff details of our secret radar research sta­tion at Bawdsey, in Suffolk, and this was pub­licly avail­able from HM Stationery Office. For good meas­ure, a free copy was delivered each year to the German Embassy in London.

We built huge radar aer­i­als, 360 feet high, which fea­tured on hol­i­day post­cards. In Arthur Ransome’s “We didn’t mean to go to sea”, the chil­dren sailed back from Holland by look­ing for the tall radio towers at Bawdsey! And there was no restric­tion on where our man­u­fac­tur­ers bought their parts, so we bought from Italy, Austria and — yes — Germany.

Britain saw radar as essen­tially defens­ive. We guessed early in the war that the Germans might try to jam our radar, and our future head of Fighter Command, Air Marshal ‘Stuffy’ Dowding, had writ­ten orders as early as 1934, when he was in charge of research and devel­op­ment, that our sci­ent­ists must find a way of stop­ping enemy jam­ming.

In August 1939 the Germans loaded a Graf Zeppelin air­ship with sens­it­ive radio receiv­ers and flew it up and down the British North Sea coast, paus­ing near all the big towers of our radar sta­tions. They heard noth­ing iden­ti­fi­able as radar because they were search­ing for a system like their own VHF, send­ing out power­ful radio pulses every second. But all they found was a con­stant, low crackly hum.

The Germans looked at their map of the British national grid, and guessed that the hum came from badly-designed insu­lat­ors on the grid pylons. But by autumn 1940, as the nights drew in, the Blitz began and here the Germans were better pre­pared with not one but three accur­ate radio bomb­ing beams to aid their nav­ig­a­tion. This was a sig­ni­fic­antly better cap­ab­il­ity than the RAF would pos­sess for another three years.

In a game of chess, the final out­come depends on a sequence of moves that limit your opponent’s options and may result in tan­gible gain. In the battle of the boffins in World War II, it was thank­fully the British who even­tu­ally emerged as Grandmasters.


 The Sinking of the Empress of Ireland – Barbara Beard – 6th September 2021


The Empress of Ireland, an ocean going 14,500-ton liner, was launched in 1906 to oper­ate the trans – Atlantic route between Liverpool and Quebec. She was a licensed mail ship and mainly car­ried immig­rants from Great Britain (includ­ing Ireland), Scandinavia and Russia look­ing for a better life in Canada. Her capa­city was 1,536 pas­sen­gers and fol­low­ing the Titanic dis­aster her life­boats were increased to accom­mod­ate 1,965.

The cap­tain of the ship, Henry Kendall had an inter­est­ing claim to fame. In 1910 he was com­mand­ing the ship SS Montrose, and recog­nised a cer­tain Dr Crippen, who was wanted for the murder of his wife, onboard. After alert­ing the author­it­ies, Crippen was arres­ted at Quebec. Crippen allegedly told Kendall “You will suffer for this treach­ery” and this became known as the Crippen curse.

On the 28th May 1914 the Empress set sail from Quebec at 16:30 local time with a com­pli­ment of 420 crew and just over one thou­sand pas­sen­gers. Eighty seven people were in first class, about one quarter full, with two hun­dred and fifty three in second class of which one hun­dred and sixty seven were mem­bers of the Canadian Salvation Army band.

Barbara Beard, our speaker, has a par­tic­u­lar interest in the Salvation Army as her father was a Salvation Army band­mas­ter for many years, and her grand­par­ents and great grand­par­ents were also prom­in­ent mem­bers. In third class or steer­age were seven hun­dred and sixty four pas­sen­gers – almost full capa­city. Many of these were return­ing immig­rants who had decided Canadian life wasn’t for them.

It was a warm even­ing as the ship slipped her moor­ings and made her way up the St Lawrence seaway. There was much excite­ment on board as pas­sen­gers found their way around the ship and many had opened portholes to let in fresh air.

At 1.38 am on the 29th May the SS Storstad, a fully loaded Norwegian col­lier, was sighted about eight miles away. Captain Kendall decided to pass this ship star­board to star­board not the usual method of nav­ig­a­tion. On board the Storstad the first mate decided to pass port to port in the absence of cap­tain Anderson who had retired to his cabin.

Fog now envel­oped the two ships. Captain Anderson sig­nalled to stop the engines and cap­tain Kendall ordered their engines to be reversed. Too late the Storstad hit the Empress of Ireland mid­ships caus­ing a huge hole on the star­board side. Sea water poured into the lower decks. Captain Kendall sig­nalled to the Storstad to start her engines to plug the gap but to no avail.

In six minutes, the power failed and all lights extin­guished. In ten minutes, the ship turned over onto its star­board side as water entered through the open portholes. Only five life­boats were able to be launched because of the ship’s list. Most of the pas­sen­gers and crew on the lower decks drowned very quickly. Captain Kendall was thrown from the bridge into the water but man­aged to reach a life­boat and sur­vived. In four­teen minutes, the ship had sunk.

The Storstad launched her life­boats and was able to save sev­eral pas­sen­gers. The pilot boat Eureka and mail ship Lady Evelyn also res­cued sur­viv­ors from the water and from the Storstad.

In all four hun­dred and sixty five were saved and one thou­sand and twelve per­ished. Many pas­sen­gers drowned asleep in their cabins. Of one hun­dred and thirty eight chil­dren on board only four sur­vived. Only seven mem­bers of the Salvation Army band were saved.

The enquiry into the dis­aster held in June 1914 found that the Storstad was to blame for the col­li­sion by alter­ing her course in the fog. This was rejec­ted by the Norwegians who blamed Kendall for not adher­ing to the rules of nav­ig­a­tion. No defin­it­ive con­clu­sion has ever been estab­lished.

The Canadian Pacific Steamships Company ordered a sal­vage oper­a­tion shortly after the dis­aster to recover mail bags and silver bars to the equi­val­ent value of one mil­lion dol­lars. Bodies were how­ever left on the wreck. This tragedy was then largely for­got­ten due to the start of World War 1, but the fam­il­ies of those who died or sur­vived have always wanted the sink­ing to be more widely known.

Barbara presen­ted a most inter­est­ing and inform­at­ive talk and we are very grate­ful to her for filling in at short notice.












Bananas, Past, Present and Future”    Pat Heslop-Harrison 16 August 2021

Pat Heslop-Harrison is Professor of Genetics at the University of Leicester, an insti­tu­tion famous for its impact on med­ical and bio­lo­gical sci­ence through such world lead­ing research as the Human Geno pro­ject and the DNA struc­tures of animal and plant life.  Perhaps less well known is the research going on into the applic­a­tions of such sci­ence into  areas such as agri­cul­ture and food sus­tain­ab­il­ity, as we face up to cli­mate change.  Our speaker could have ensured our interest by choos­ing to focus on any one of a number of staple crops: wheat, maize, rice, pota­toes, len­tils, soya etc.  But it was to be the humble banana which was to be his choice of main dish on the menu.

Professor Harrison opened his talk by explain­ing the import­ance of the banana as a lead­ing diet­ary staple and con­trib­utor to world food supply.  Around 120 mil­lion tons are now pro­duced world-wide, with cul­tiv­a­tion mainly in trop­ical and frost-free coun­tries. But only around 15% of pro­duc­tion enters world mar­kets.  India and China are the largest pro­du­cers, all con­sumed domest­ic­ally.  Elsewhere, the main pro­du­cers are Latin America and the Caribbean Islands, export­ing to North America and Europe.  These mar­kets opened up in the late 19th Century with improve­ment to ship­ping, stor­age for con­trolled ripen­ing and onward logist­ics, the trade becom­ing dom­in­ated by the likes of Fyffes, Pratts, Dole and Chiquita, who have about 60% of the market.


Bananas are a valu­able source of Potassium, fibre and vit­am­ins B and C.   According to the Guinness Book of Records, they are now the most con­sumed fruit — not only by ath­letes want­ing an energy boost from their high car­bo­hydrate and sugar con­tent!  Although a fleshy elong­ated fruit -the banana is botan­ic­ally a berry pro­duced by herb­aceous plants (not trees) in the genius Musa.  Originating in SE Asia, they come in all sorts of shapes and sizes (and fruit col­ours) and can grow up to 16 feet.  Cultivation began around 6000 BC when the ori­ginal wild fruit had large black seeds and so was dif­fi­cult to eat.  Seedless vari­et­ies have been evolved over the cen­tur­ies.  In the Tropics, smal­ler, firmer, bana­nas used for cook­ing are called plantains. The famil­iar yellow dessert fruit we enjoy are typ­ic­ally from the Musa Acuminata ‘Cavendish’ vari­ety. This became pop­u­lar in the 1950s when the Gros Michel vari­ety became unvi­able due to Panama Disease.  These typ­ic­ally arrive in our shops via refri­ger­ated (13.5 %C) sea con­tain­ers with the on shore arti­fi­cial ripen­ing pro­cess con­trolled by ethyl­ene gas.  This enables demand and supply to be care­fully con­trolled, and waste min­im­ised, before dis­tri­bu­tion to retail­ers.


Our speaker, who shares research with uni­ver­sit­ies in China and France, moved on to give us a taste of the sci­ence behind the cul­tiv­a­tion of the valu­able crop.  There are over 2000 known vari­et­ies of banana. These have been stud­ied and recor­ded by their (mil­lions )  of cell, gene and chro­mo­some struc­tures to give ‘band­ing’ pat­terns.  (A sim­ilar approach is used in vac­cine research).  This allows sci­ent­ists to estab­lish which vari­ety is related to what and facil­it­ates the iden­ti­fic­a­tion of nutri­tional value, disease/virus/insect res­ist­ance and cli­mate hardi­ness. What fol­lowed was much above your blog writer’s head, but sens­ing that we might be enlightened by the delights of CZH2 pro­teins and single Nucleo Polymorhisms, Pat sug­ges­ted we might refer to the Banana Genome Hub on the web. (it’s worth a look!


Professor Harrison con­cluded his present­a­tion with a glimpse into the future. Food sus­tain­ab­il­ity and reli­ab­il­ity will con­tinue to be major con­cerns.  We are all aware of the effects of pop­u­la­tion growth, eco­nomic expan­sion and, increas­ingly cli­mate change: much of the world seems aflame, or suf­fer­ing from extreme storms and flood­ing. These events are clearly already having an effect on agri­cul­ture -animal and plant- and water sup­plies and levels.  And there are other threats: the pop­u­lar ‘Cavendish’ vari­ety is becom­ing affected by the Sigtoka virus and much research into hybrid­isa­tion and genetic engin­eer­ing will be required to combat it. The same threats apply to other crops and give rise to other chal­lenges such as fungi, bac­teria and weed reduc­tion.  Major pro­grammes already under way have allowed food reduc­tion to keep pace with pop­u­la­tion growth but sadly there has been polit­ical res­ist­ance to these devel­op­ments, not least in Europe.

As might be expec­ted, Pat’s talk stim­u­lated more ques­tions than time allowed.  These included:  Was the Potassium con­tent in bana­nas harm­ful? (No)  Why was the Cavendish vari­ety so pop­u­lar? (Reliability in cul­tiv­a­tion, ease of trans­port –but try others avail­able in ethnic shops)  What might be the effects of cli­mate change? (Could extend or reduce areas of pro­duc­tion). Do bana­nas help ripen toma­toes (yes, they give off ethyl­ene gas).  And what is the cor­rect way to peel a banana? (From the flower end towards the stalk).






CONVOY  — Dr. Phil Judkins (University of Leeds). — 2nd August 2021

Britain is an island and, during the war, almost all mater­i­als coming in or going out of Britain had to go by sea. The Germans knew this and used their U-boats, E-boats and air­craft to isol­ate Britain.

The first WW2 ship to be sunk by tor­pedo was Athenia, but the Germans denied respons­ib­il­ity, prob­ably because they were afraid that the USA might join in the war. Mines were also used — con­tact mines which exploded if a ship hit them, and mag­netic mines which were triggered by the steel hulls of ships. Many British navy ships used ‘degauss­ing’, cur­rent passing through copper strips to make them non-magnetic, and many ships were tem­por­ar­ily made safe by “wiping” their hulls with an elec­tric coil. The Germans developed acous­tic mines which were exploded by the ship’s engine noise.  Minesweepers were used to remove the mines with, for acous­tic mines, a jack­ham­mer sus­pen­ded in a box under its keel whose noise exploded the mines at a safe dis­tance.

The first pro­tec­ted con­voys were for the “Coalscuttle Brigade”, slow, small, coastal coal ships which were pro­tec­ted by armed trawl­ers. In 1940 many ships of convoy ‘Peewit’ were sunk by E-boats and German bombers, show­ing that U-boats were not the only threats to ship­ping.

The S.S. Automedon was cap­tured by the Germans with, in its cargo, naval code­books, so the Germans could read where all British con­voys were headed. However, the British had man­aged to break the German ’Enigma’ code, which led to the sink­ing of the Bismarck. Breaking an ‘Enigma’ mes­sage would yield only a 100 square mile rect­angle con­tain­ing a U-boat, but new radar sets powered by a “cavity mag­net­ron” whose mag­nets were developed by research­ers at Sheffield University and made by Sheffield firms, enabled pre­cise search inside that rect­angle, while Asdic (sonar), in which a pulse amp­li­fier sends out a sound­wave under the sea and detects the echo from a U-boat, made the final pin­point­ing of the U-boat.

When America joined the war, it, did not at first use con­voys pro­tec­ted by war­ships.  Many tankers were sunk because they trav­elled in day­light, had all their lights burn­ing at night, or were sil­hou­et­ted against coastal illu­min­a­tions. Britain sent ships and air­craft to pro­tect American tankers.

Arctic Convoys first sailed in the Arctic winter during the long winter dark­ness, but later suffered heav­ily in the Arctic’s long summer days. In the Mediterranean in 1942 Malta was sur­roun­ded and run­ning out of fuel so the ‘Pedestal’ convoy, includ­ing air­craft car­ri­ers was sent, but German and Italian air­craft, E-boats and U-boats sank one car­rier, three cruis­ers and many freight­ers. The tanker ‘Ohio’, with a full load of fuel, was hit sev­eral times and split almost in two, but man­aged to reach Malta sand­wiched between two des­troy­ers. Ohio then dis­charged all her fuel before sink­ing!

Dr. Phil told us about many other con­voys, includ­ing the Atlantic convoy ONS5 where cen­ti­metric radar, using the mag­nets developed by Sheffield University, helped des­troy 13 U-boats which attacked the convoy. Those losses were unsus­tain­able, and the Germans with­drew U-boats from the Atlantic.

D-Day saw the largest convoy, 7,000 ves­sels pro­tec­ted by 1,200 war­ships of the Royal Navy and other navies, to carry British and American and other nation­al­it­ies’ troops to invade the French beaches.

There were about 1200 U-boats and 783 were sunk with others were dam­aged beyond repair.  After the war only 4 were pre­served intact.

Convoys were the import­ant way the war was won but it was by a very narrow margin and at a huge cost in human life.

The flora and wildlife of a Peak District garden and its environs — Peter Bull — 19 July 2021

Peter Bull is a retired ENT Surgeon.  He prac­tised in Sheffield but now pur­sues a pas­sion for pho­to­graphy.  He lives on the west­ern edge of Hathersage over­look­ing the Hope Valley, Stanage Edge and Hathersage Moor.


Peter has a gift for taking superb pho­to­graphs of wild­life and flora.  His dis­play of over one pho­to­graphs included sub­jects found in his garden and within a mile of his house.

As the title of his talk indic­ates, the pho­to­graphs were all taken whilst we have been in lock­down start­ing in March 2020 and con­tinu­ing up to this month.

Whilst his audi­ence looks in awe at the won­der­ful pho­to­graphs of birds, Peter has included a record­ing of the song of sub­ject to make his talk even more fas­cin­at­ing.  He has two ponds in his garden and he has pho­to­graphed all the ingredi­ents for the witches brew from Macbeth.  He starts with prim­roses, a Black Bird, a Jay, a Dunnock and a Willow Warbler before show­ing superb images of but­ter­flies. He pro­ceeds to show dif­fer­ent images grouped on a monthly basis.  This gves a big range of hab­itat from birds and dragon­flies on the bank of the River Derwent by Leadmill Bridge in summer to stags and white hares in the winter moor­land.

What is so mem­or­able about Peter’s talk is not only the bril­liant pho­to­graphy but the enorm­ous range of anim­als and flora to be found within a mile of his house.

How far is a bridge too far? Matthew Gilbert PhD 5th July 2021

This was every bit an inform­at­ive talk laced with some quite chal­len­ging math­em­at­ical con­cepts which inform on best bridge design.

Computational mod­el­ling and optim­isa­tion are able to pre­dict how a bridge’s com­pon­ents and struc­tures will behave under spe­cific con­di­tions, and thereby improv­ing design, effi­ciency and man­u­fac­tur­ing tech­nique e.g. with 3D print­ing

What are the span limits for any bridge form?


For example, those made from stone have a very lim­ited span. Steel fares a bit better. So what altern­at­ive forms are more effi­cient and allow for a greater span?


Robert Hooke 1635–1703 invest­ig­ated the shape of an arch by hanging weights from a straight beam. He then inver­ted this shape to deduce the optimal arch shape for effi­cient bridge con­struc­tion.

Forces gen­er­ated by the weight of a stone arch bridge limit span to just 120m.

Other mater­i­als e.g. rein­forced con­crete or metal can extend that limit to around 400m.The steel rail bridge at Newcastle upon Tyne would be a good example.

Fig 1 Types of arches 

Cable sup­por­ted

The most usual form is the sus­pen­sion bridge, for example the Humber Bridge

Fig 2 Humber Bridge

The main towers were built first and linked together with a pair of cables spun each side of the bridge and ver­tical cables hanging down to sup­port the deck. Deck sec­tions were then made to com­plete it. It was opened 40 years ago and was the inspir­a­tion for Dr Gilbert’s future career in civil engin­eer­ing on a school trip.

Other examples are the planned Halsafjorden in Norway which will span 2050m. Wind engin­eer­ing aspects are import­ant with a bridge of this size, with wind tunnel aero­dy­namic test­ing, wind buf­feting, flut­ter and vortex induced vibra­tion lead­ing to ongo­ing modi­fic­a­tion of the bridge deck geo­metry. There will be a float­ing tower in the middle anchored to the fjord bed below.

The span of a simple sus­pen­sion bridge is the dis­tance of sus­pen­ded road­way between towers and the 2km span of the Akashi Kaikyõ Bridge in Japan is the limit.

Cable-stayed form

Long span arches need cable-stays. Cables dir­ectly con­nect the towers to the road­way by a series of diag­onal stays between tower and deck. This bridge form is effi­cient as the main con­struc­tion steps are sim­ul­tan­eous. The main tower with pro­gress­ive lat­eral deck exten­sion on each side increases the span. Deck exten­sions then meet and are joined together.

Fig 3 Queensferry Crossing

The Queensferry Forth Replacement Crossing is a 4-span cable-stayed bridge with main spans of 650m

Hybrid sus­pen­sion and cable-stayed bridges are even more effi­cient. Diagonal cables are dropped to sup­port the deck

while being exten­ded. The middle part is sup­por­ted by main cables. The longest bridge in the world, 164.8km long, is the hybrid Danyang Kunshan Grand Bridge in China

Danyang Kunshan Grand Bridge in China









The best form of bridge

The most import­ant ques­tion is the optimal min­imal volume of mater­ial required to build the most resi­li­ent struc­ture. As bridge span increases, pro­gress­ively more of the struc­ture is neces­sary to simply carry its own weight, thereby lim­it­ing the span.

Steel cur­rently is the mater­ial of choice, so the only altern­at­ive at present is to adapt the effi­ciency of bridge design. A simple bracket with an attached weight is a good ana­logy. A large dif­fer­ence in volume is achieved using an ortho­gonal bracket shape (Fig 5).

Fig 5 — orthogaonal is on the left

Computer mod­el­ling has shown that com­plex ortho­gonal lay­outs are best for achiev­ing equi­lib­rium of bridge struc­ture (Fig 6).

Fig 6

But not all ten­sion and com­pres­sion ele­ments are ortho­gonal because the weight of the struc­ture itself needs to be factored in.

Development of the ideal is ongo­ing. There are eco­nomic issues, and factors such as wind load­ing and mater­i­als; when sub­sti­tu­tion of steel by carbon graphene becomes tech­nic­ally feas­ible, the app (“try it your­self”) sug­gests the pos­sib­il­ity of a 10 km span.

Most of the forces on a bridge are dir­ec­ted down the tower. A new bridge form needs less mater­ial largely because the forces from the deck are trans­mit­ted from the super­struc­ture to the found­a­tions. This is achieved by keep­ing load paths short and main­tain­ing wide angles between the tensile and com­press­ive ele­ments. Sharp angles give large com­pres­sion forces. Changing the compression/tension ratio optim­ises change in shape and type of bridge

A bridge too far

A bridge has been pro­posed to link the UK with Ireland. Bridge length is a bigger prob­lem fur­ther south between Wales and Eire.  Scotland on the other hand adds to jour­ney time from England and the con­tin­ent. There are con­sid­er­able fin­an­cial, struc­tural and polit­ical chal­lenges but it is feas­ible. A com­bined tunnel bridge would be pos­sible.