Enclosure MoUI^ig^gs^g^eJJJg^espeitch secret cioaure No.l in Me* /.ealuud ouMUaalon No.ii6/8B08 oX COPY i-rum .... TUe ouiuiuaouxn^ uiiicer, "acuilles". at Auckland. Date .... £nU uctuoer, 1*56. Wo.l5b5/13tt. To •.....TUe CuiMbuUure UtfBmandiu&,Ne« Zealand Station. uuujuct.. ueport or Pacific islands Air survey c .Pled out oy li.ki.s. " •.cuilies" oa pas^u^e i'ruifl Llureauo* to New ttaclosures*. section 1... Purvey Narrative. section II.. suitability lor Air buses. section •autot>rapUic aunaary section i\i ...iieioarks by orficers. riiotocrttphs. .. Giiriatiuos i;,lund v FMiiix.it, Island Canton island iiuil Island. iiere*itU is snomitted tue report of Aerial survey carried out in accoruauce with Admiralty Message timed £lbO of l7tU *Julyt 1*36« (signed; I.u. oleuoie, Gaiit^in> closure to "AcUiliesw Ho.i&8b/i58 uated znd October, iyi>6. u 1 o K B 'i BZ Section I...............Survey Narrative, section 11..............suitability tor Air Bases Sub-aection A..........Christmas island. fi..........* aiming Island. 0..........kiufcjiian island. £..........Canton island. £• .........iiull island. t..........Nuko-nono island. U..........kinerva Keef. aectiun ill.............rhotOi>rapuic buwiaary. Section IV.............Remarks by oiiicers. section 1. .survey Narrative. mini orders were received to make a " iuxck i'uutu^rapuio Survey" of certain Pacific Islands* iue time factor raised certain pro- bieius wuicu were accentuated by tue pour charts available and tue Jack of navigation marks* In particular tue charts available snowed very little detail on tue we .ther iide ol' inlands and tuis resulted in a decision to iiktke all runs against tue prevailing wind; making use of tue better charted marks on tue lee side as departure points* , Cloudy couuitions9 considerations of endurance and or tue time available, bow- ever, often Liade it necessary to carry out runs in any direction which offered - as at Canton Island* Oblique photographs were taken to supplement tue mosaic* . height In spite of tue considerable amount of cloud encountered it was decided aot to take "verticals** below tue height of cloud formation lis,500 ft; because of tue prohibi- tive amount of film required to cover a ^iven area - £5 tiiaes that required at 10,000 ft* Consequently all tue photographs of wuich tue mosaics are composed were taken from an indicated uei^ht of 10,000 ft* At tannine Island tue appearance of a tuick layer of stratus and strata cuiuulus alter tue second run made iurtuer vertical puoto^rapby impossible. This *as based on tue Uei&tit cor- rected by applying Uie correction lor temperature to successive 1,000 loot levels* Itte total correction varied veiy little irora + 590 it. in dixiereut surveys and tuis cor- rection uas teen taken as constant turoughout tue series. The eliect o£ diurnal ciian^e of baroiaetie pressure on indicated nei^bt during duration oi tue £li&Ut uas been neglected as inconsiderable. an overlap v£ 60>- tore and aft and 50, laterally was aimed at. Ifte iormer tfas well maintained tarou^nout tbe series but uuere were wide departures iron tue latter li^ure uue to tue lack o£ suitable "pin points.¦ itie lai&e a ore and aft overlap was ¦ade aitb a vie* to providing stereoscopic exiect in order tuat it suould be possible to distinguish dry land irora submerged coral in tue iinxtiued prints. in tue better prints tuis object Uas been realised. Survey ffind In oraer to save time involved by finding wind at survey uei^bt it was decided tuat tue wind at 10,000 it. suould be iound Jit fey uy siuoke shell fired by tuu ..uip aid the result signalled tu the aircraft, This arrangement worked extreuely .veil and enabled tue aircraft u> reach survey height *ith all Decenary calculations.made for i>rift aod Lxposure time interval. kosaica. xiie full ticale mosaics suould be consulted fur any points of detail. The small copy mosaics are simply fur the purpuse uf easy referunce in conjunction *ith the uoli^ues tfhich amplify the text uf the repurt. wblluues. isacn utiique bears a letter which appears on tue copy mosaic and indicates the pMition from wnlch the photograph is taken and tue direction of the vie*. No ubli^ues of jfannin* Island are . included as they .*ere uf extremely pour quality. - -¦ w, Section 11. Suitability fur Air aaaes. i)ate of survey a2rd and £4tu August, lfc56. survey height 10,390 Feet. ^caie 1 inch represents 69£.7 Yards. CaatttJaM as survey. The survey took place on two days; the afternoon uf the first day and tue fore- uoon and afternoon of the second bein& avail- able lor survey flying. 'liirou&hout this period about 8/10 v ¦ low low cloud persisted over the South part of the island, and nearly &s much over the extreme Worth iuaking it impossible to take verticals of tuese areas from a reasonable height. The lagoon area., uowever, was noriimlly much freer from cloud, except i'.M. on the second day when che sky was completely overcast. id£]J£r&l. Considering tue area surveyed as a wuole, tue Western naif is lagoon of varying depths, the Kastern hall' land and lakes with a transition area in the centre lying in a direc- tion |«Jb - S.rf. consisting of land, water and coral almost awash. Two thirds of the lagoon are shown in tue mosaic - tue Northern tuird which is not shown consists of islands and very extensive coral ledges - its general depth is prohahly auout two feet, within a radius of £•$ miles iroiu the centre ui Cook Islet there is an ttrea within the lagoon entirely free from coral obstructions except possibly on its extreme Eastern side and hav-iu^ througUuut a depth of wore than 9 feet and a general depth of twelve feet* It may be assumed tuat the darker areas represent a depth of over two fathoms. Outside tills area to the Kastwaru is the transition arM with coral ledges ahout one loot from the surface suowiag white in Uie photograph. To the South and aouth-^est are wide spread coral patches having over them depths from one foot to to about lour £eeu In the extreme iiouth ^est ox' me lagoon is a patch oi' about one mils square *ulch is ne;a»ly free from coral beads but is sualiorfer than appears from tue photographs - about six feet. ¦ ihis is uuueycombed with lakes of Varying sizes aud deptus and of every colour iron pale green and blue to dark red. They are lull of numerous coral heads. Ihe area lying to the iioutu East if the mosaic and extending lor about ten miles to tue Kast is somewhat similar but has in places dry areas sufficiently lar&e for an aerodrome and having a surface apparently suitable. suitability iqr Air i^e. Kun&ways. fihe area previously described as lyxii^ within tue radius of &.5 miles from tue centre of Cook islet fulfills the specified requirements xor xen^ai of runways. 'ahe depth in places is less tuan tue specified twelve feut. iio otuer area is suitable. Uection of uan^ars. There are numerous suitable sites lor hangars and slipways. Ubstruptiona* No serxous overhead obstructions exist* • — s u Blast xiu*. If tue removal of the coral heads on the Eastern limit of the area were considered necessary necessity it would be ^uite practicable. Date of Purvey £bth august, 1^36. purvey ueijat 10,390 *eet. oouie l inch represents 69^.7 yards* ¦ iue sc^xe ,j j cuecked over a known Base of 4*5 miles reaultiuo in aa errur of-f0.05/« compared to tuo chart* Qou^lWous xor purvey. Cluud cwuoitiuas were bad at first, but a small clear patch allowed two runs to be made before an extensive 10/10 layer of low cloud made further work impossible. A defect in tue camera suutter blind has resulted in uneven exposure. prises all tue lagoon in -ny suitable for runways. lhe remainder consists of coral patches and ledges, mostly a.vash. oi tue centre UC bn^lisn harbour entrance and between tue ocarinas .045 and luo decrees la comparatively free from sural obstructions. j tiuch as these are could oe cie^red by blasting, outside Wis area tue white patches in the photographs represent coral heads, patches,etc. ith little or no water over tnem. To clear these xor runways would involve very extensive blasting. (ihe area surveyed, wou^u small, com- kunways . ao area lyiu* rfiuin 1 mile radius frreqtiop The land urea is suitable for the erection of hangars auu worksuops. biipways would nave to oe built cle*ir of the deep water uuumiol through which tue stream runs strongly and would probably involve blasting* 'lake oil turuu^U i>eeii ,«ater Channel. inis chaunel has a width of a^out 7uu feet but an effective width in tue direction oi the prevailing wiud of considerably less* 'iuere is prob&uly a considerable swell running in tue oixing on most occasions; on tuls occasion tue srfell .vuuiu Uave nude a take off Hazardous. 'ihere are minor obstructions in the way of paliiiS .ad buildings - maximum beigbt 70 feet, j frub-aection ft. fcllMM Date of examination 2bth August, 1936. uQmarks. No aerial survey was possible* under the circumstances* 'ihe reef encloses a lagoon of dioeas- i ions nine iaiius by five miles at tue widest point. ibe depth is considerable througuout with no appearance of coral obstructions. Run- way requirements are completely met. The onl> dry land of considerable area is a auall sand islet at tue Eastern eud of the reef about lbO yards long and 5 feet high. 'ihe reef is othei wise wise barely awash or submerged. Ihe l