windpower in eastern crete - 21-499

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MICROFICHEREFERENCE

A project of Volunteers in Asia

by: N. CalvertPublished by:The Newcomen SocietyThe Science MuseumSouth KensingtonLondon SW7United KingdomPaper copies are 0.35 British pounds.Available from:The Society for the Protection

of Ancient Buildings58 Great Ormond StreetCl, EnglandReproduced by permission of The Newcomen Society.Reproduction of this microfiche document in anyis subject to the saxe restrictions as thosee original document.


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Windpower n EasternCrete

BYN. G. CALVERT, BEng, PbD, FIMechE

Excerpt Tramactio~~~ of the Newcomen SocietyVOL XLW, 1971-1972


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Windpower in Eastern CreteBY

N. G. CALVERT, B.Eng., Ph.D., F.I.MechE. (Member)That Crete was a land of windmills was one of the many useful things which the author had learntfrom his daughter. As an undergraduatestudent of the classicsshe had noticed and photographedthe massei windmills of Malia when visiting the hlinoan site.The Aegeanwindmills, in common with those f north western Europe could, in modem termino-logy, be classedas full-admission axial-flow machines. Here the similarity ends so far as the wind-wheel s concerned. Forbes*suggestshat the Aegeanmay be a later adaptation of the western owermills. The western mills evolved through the post to the tower stageand the post mill has neverbeen rcxorded n the Aegean. There are ndeed tower mills on the coastof Crete near to Spialonga

but the majority 0:. mostly ruined) corn mills sighted by the author in Crete were not on the coastbut on the mountam ridges and they were describedas monokairos, that is they were permomentlypointed in one direction. Their conceptcould be evenmore primitive than either tower or post sinceit contains no element of direction seeking (Plate XXX11 (a> and @)).The aerodynamic characteristicof the Aegeanmills is in their useof a fairly large number (six totwelve) of canvas ails rigged so that their shapecan comply with the forcesacting on them. Indeed,the mill inwrporates aerodynamicand structural feanues of the modem racing yacht; that is, it is afully trkgulated suucture of spar and stay flying triangular sails. These sails, which are capableofroller reefing, are sheetedamidships and the mill sails orever with the wind on the beam.As a strucune, it can hardly be improved for the efficient use of material. Aerodynamically, thelow speedefkiency is high and it has an inherent stability againstaccidentaloverspeed. Overspeedis analagous o sailing too close o the wind with the inevitable consequence f the sail being takenaback and an automatic loss of propulsive force. The finely pitched aerofoil, on the other hand (ina windmill context), has an inbuilt urge to self destruction should the restraining load be accidentallyremoved,a property analogouso that possessedy a D.C. series-woundelectric motor.The machinesseen n Crete were small by west European standards. The range of size was from4 m. in diameter for the smaller rrigation pumps to 12 m. in diameter for the corn mills (comparedwith 29 m. diame@x or a large Dutch polder mill). This size imitation is by no means nherent inthe construction The conceptof optimum size seems o have been nstinctively appreciated n theAegean. The power of a given type of windwheel must depend on the area t presents o the wind.That is, on the squareof the linear dimension. The weight (and cost)of the material dezyznds n thecube. To double the sizeof a windwheet is to quadruple its power and to multiply its useof materialbyafktorofeighLIt might well be better to build four little windmills than one big one. Twelve or more (mostlyruined) corn milL can often be seen n a row along a mountain ridge in Eastern Crete and in any oneigafion area the number of machines may be measured n hundreds or even in thousands. The

survva of windpower in Crete, so long after its decline elsewhere,must in part be attributed toinuinsic~~ofthelocalmachinesasw~astolocalcircumstances.

l Forbes, R !. in Kiuwry of Tedmob, II (1!3!56),18.137


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,--- ___--- ____-WIlUDPOWER IN EASTERN CRETE

THE &GEAN WINDWHEELThe Aegeanwindwheel,(Fig. 1 and Plate XXX) has an even number (six to twelve) of radial armsor sp0kes.l From the hub of the wheel there ; an upstream extensionof the windshaft which maywell be called a bowsprit. Forestaysextend from the tip of the bowsprit to the outer ends of thearms. Again these arms are stayed to each other ~YI he plane of the wheel. By a rather severe

stretching of the nautical analogy hese ip,connectiox!s ould be called the triatic stays. Each radialarm flies a trisail sheeted o the adjacent riatic stay or t3 the arm behind.The windpump wheelsinvariably utilise an ron winrishaft with some orm of hub, hence he spokesor arms are ah in one plane (or occasionally he arms may slope slightly, about 9, and thus he in aconical stice).The 001x1ulls however,usea massivewooden windshaft and no hub. Pairs of arms are mortisedinto this shaft. No two r&s can ie in r.he ameplane for this would involve undue localisedweaken-ing of the shaft_ The arms are displac-d axially at the hub but at the tip they are strained o lie in thesameplane. In this respect he Aegean mills seems o differ from illustrations which the author hasseenof somemills in Portugal. The Aegean till has a capacity for sail changeequivalent o that of asailing ship and can utilise almost as big a range of wind speeds. Each ndividual sail can be reefedwltil the bare pole condition is reached. No con mills were observedat work but, in the caseof thewindpumps, sail appears o be set appropriate to a speedof 25 revolutions/r&. or less. The sails nuseare generally (but not invariably) symmetrically listributed around the periphery (PlateXXX11 (c)and

Fii 1. Typical Atgton Windwheel

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..--WINDPOWER IN EASTERN CRETE

IRRIGATION MILU IN EASTERN CRETEThe largest Ooacmtmtion of irrigation mills in Eastern Crete is in the mountain plateau of Lassithi.The number there is variously quoted in current guide books and tourist brochures as six, ten,twelve or &ken thousand. Whatever the Qure may be it is impressively large.group is probably that on the coastal plain in the neighbourhood of Malia. The next largestOther, much smaller

groups of irri@on mills have also been visited at Limnes, Agios Nikolaos, Pachia-rimes, Sitia andPalaiBastru.Characteristically, each wind pump is mounted over a stone-lined well some six or sevenmetresdeep md about two metros n diameter. The pump discharges nto a stone built, cement ined cisternof about eight cubic metrescapacity. The cistern s built above ground so that the adjacent gardenhas a gravitational supply. The fact that each garden plot may have ts own well, wind pump andcistern means hat groups of mills are often found very close together.tion mills are less tbaa %y pears old. The great buk of the itiga-A superfkial view from a little distance suggests hat theCretanwindpumpsareverymuchalike. Clcsrr examination reveals almost indefinite variety ofcollsallctional dctaii.The fust step towards the understanding of a complex situation is classification. The authorsuggests he Mowing, basedon the skills and resourcesused in construction:(a) lho~ which could have been built by a blacksmith-wheelwright. These use both wood andmetal in cammnmion and employ the wedgeand the rivet for fastening.(6) Those vi&h could have been built by the ingenious mechanic of the fifth decade of thiscentury. I&se use ittle if any timber and employ metal parts gas-weldedor hited ogether.Tkse p may suggestautomotive origin and the salvageof military debris. The two types(a) and (b) umld correspond respectively to periods of reconstruction following the years of1914and 1939.(c) A very fkw which are cbamcte& by a stone tower instead of one of lattice steel construction.

There arc ah hybrids of the above.A machine of type (a) is shown d@knmatically in Fig. 2. The tower is constructedof angle ironsurmounted by a &I% of similar material neatly bent into a circle. The windshaft, inclined at15 to the lrxdmd, is of square section bar.th-===Ye

On this, a central crank, formed by bending, givesmotion to the pump. The bearing surf&es both for the shaft and theuankpinsuggestworkontheforgeratherthanonthelathe. Thenecessarilysplitbearingsareofwood and the bowsprit is of angle iron sp!it and bent into a double claw at its outer end. The hubof the wiudwbcel is a cylhder of wood, protected Corn splitting by irons bands, and mortised tomcive the wiudwkd arms. The arms, themselvesnormally eight in number, (exceptionally six orten~areofrivenwood Tbestaysareeitheroffencingwireorofchain. Axialrhrustmaybetransmitted from the hub to the adjawnt bearing by a wooden distancepiece threaded over the shafk.Sommmes proclrisipobr axial thrust is not apparent ftom ground level.toheused,buttfrarisnevekanysignofpaintorp A greasy ubricant appearsrescrvative. The wooden tailpole catries a tri-arrgularwiad~~which~acOrdorchainformanualcontro1.The pump krcl is often of copper, open at the top, delivery being by a spout at one side. Boreand stroke arc erh about 0125 m. (nearly 5 in.). Therisno No bnlre of any form has been observed.Ofcoasuuction.Typc(b)miUs4ncofsimila+Type (c). tppcamm but practically every detail difkrs from type (0).At M&a, Agios Nikolaos and Limues a minority of the mills are mounted on a tower ofstone ifisted ofan& imn. This did not so mu& irdicate greater age as greater ingenuity on thepartofdrcbpilbrseckingtoavoidthcbigbcostofangleiron. OnesuchstonetoweratMaliahad

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WI-NDPOWER IN EASTERN CRETEscratched n the cement rendering over the doorway. This was unusual in that itnot built directly over its well; there was a short horizontal run of suction pipe. The stonehad a small doorway (too small for a man too the pump. Spps are arranged on the outside of such towers to give accessoThese may take the f&n of either projecting stonesor of foot holes left in the structure.in either cast is helical so that the climber winds around the tower as he ascends.Two stone-towered rrigation-mills were observed at Limnes which could have been much olderThese had a wooden curb and wooden superstructure. Unusually they had ten arms andThey had a tailpole but no vane.ridges are rows of (unserviceable) Limnes is in a mountain valley and on themonokairos corn mills. These corn mills were reported

Fii. 3. Ikgathn Wheel OL Stone TowerAt Agios Nikolam severalsmnc (kigahm) mill towers survive without superstrucnue in suburban!bne ofthese, along with a stone platfbrm for sail changhig, are inThe pumps in the older tcw are aimmdy ordinary cast-iron well-head lift-pumps with the

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-- -- .-- .--_ --.-----_WINDPOWER it7 EASTERN CRETE -__-I_- --~---- --_I_THE ~OIMANCE OF IXE CRETAN WIND PUMP

The authors visit to Crete was early in the irrigation seasonand only a few machines were seen atwork. Opportunities for measurement n the field were limited to wind speeciand rotational speed.Observationswere made on a number oi machines, n the fully rigged state and in rotation, at windspceds commmcq at 2.2 metres/sec. i miles/hour). A useful output of water appeared at a windsptzd of 2.75 metteqsec. 6 miles/hour). When the wind speed ose o 3.5 metres/sec. 8 miles/hour)a four-mete diameter machine would run at a speed of up to 25 rev&in. No rotational speedshigher than this have been obszved. Higher wind speedswere in the authors experienceassociatedwith reduced sail.tirresponding 6gures for a Northern Mill tie available. F. Stokhuyxen: gives 5 metres/sec.asthe wind


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WINDPOWER IN EASTERN CRETE---CRETAN IMILLS XN ENGLISH LANGUAGE PUBLICATIONS

Crete has been well served by English-speaking travellers; many have written books on theirexperiences,but most had a blind spot as regards windpower. Whether it was so rare as to escapenotice, or too common to comment on, is not at once apparent.Pashley, whose ravels began n 1834,sought mainiy for archaeologicalsites which could be identi-fied in the classical exts. He recordedmuch folklore and made occasional eference o aqueductsandwater mills. Once only, and that in a foomote, has the author found references o a windmill (pre-sumably a corn mill, in the extreme north-west).Captain Sprat@ 1865) ofthe Mediterranean survey travelled widely and climbed mountains on hisjwmeys of u%gulation. He too had a keen eye for antiquity; he noted every wartermill he saw;but never once did he mention any kind of windmill. In writing of the mountain plateau of Lasithihe mentioned the dminage dikes but did not record any instance rf wirid-pumped irrigation.Batty9 who travelled through Crete in 1913 was interested in Natural History. He noted theunload@ of a millstone from a coastalsteamer and took delight in watermills, but never once did hemention a windmill However, his book is illustrated with photographs and on one, featuring athreshing floor, there are four unmistakeable irrigation windyumps. There is no clue as to whereit was. These machines, although rather out of focus, can be seen o be of timber construction andapparently without tail vanes. They have eight arms. This is as far back as the author has beenable KOrace evidenceof the irrigation mill.Dorothea Bate, who published with Battye in 1913,described the view of the Plateau of Lasithi asseen from the mouth of the Dictean Cave spread out like a map below . . . a vast and k-regularchess board. She nexr once mentioned a windpump, although today these are the dominantfdure of the view.HoldP (1928) ncluded a picture Mount Dikte with Windmill. This is aview across he plateauwith a single wizdpump in the foreground and three or four faintly identifiable in the background.The mountain feanue show that this view point is the same as that used n current picture postcardsof The Plateau of ten thousand windmills.ElIi& (1933), on his ~ourncy rom the former Imperial Airways baseat Spinalonga to Heraklion,recorded the row of wimbilk at work near Neapolis. These must be some of the rows of now-ruined corn-mills along the mountain ridge, for the windpumps in the valley bottom are not in a rowbut have a random grouping.In the late 1930sgeography extbooks began to refer to irrigation dependent on numerous wind-smills- on L&hi.Currently, in 1972when they are n decline, windmills feature in all the relevant tourist brochures.

The Author wishes to thank Mr. J. Woollam for the preparation of the diagrams, and gratefullyto achowledge the help he received rom the British School of Archaeology n Athens.

l Pas&y, R, Trads in Cretz, John Murray, Iandon, 1837.8 Spmtt, T. A. B., Trade and Researh in Creze, London, 1865.= Batye, A. T., cmrrpirlg in Cme, Lmdm, 1913.l Hoh& Gree.#, Lamdo& 1928.8 Bllidi, U II., Creze, Puss und Resew, Heath Cronten, London, 1933.143 .


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windpower in eastern crete - 21-499

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