142 PERCY SLADEN TRUST EXPEDITION. 
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spots arranged in a looped series of depressions along their narrow ventral sides, 
Among the adult fish were Argyropelecus affinis, x known form allied to A. sladeni, the 
latter a new species secured in the Chagos from 400 fathoms; Melanostomias valdivie 
was also taken, an elongated little fish of blue-black metallic appearance, with two rows 
of phosphorescent spots segmentally arranged along its lateral line and near its ventral 
surface, and a long barbel with a phosphorescent bulb below its rather lantern-like 
heavily-toothed mouth. 
On the following morning we were in the middle of the passage between Farquhar 
and Cape Amber. A sounding gave 1818 fathoms, a previous one to the north having 
given 1858 fathoms. Further south, near the Cape, there were already two soundings 
of 1478 and 1750 fathoms, so that it was obvious that there could be no close connection 
of the islands to Madagascar. Here Capt. Somerville swung the ship for variation, 
finding that the compass pointed 8° 38' west of north, a variation of 8° 38’ W. This was 
interesting as being nearly the same as that which he found off Mauritius, nearly 10° to 
the south, while in almost the same latitude east of the Saya de Malha Bank he got 
4° 59' W.* Probably the difference was due to purely local conditions, perhaps the 
large land-mass of Madagascar, or perhaps some peculiarity of the rock beneath the 
sea. In respect to the latter, it is interesting to remember that the variation (not only 
horizontal, but also vertical) was especially carefully examined at Funafuti by Capt. 
(now Rear-Admiral) A. M. Field, with a view to finding where rocks, other than lime- 
stones, most nearly approached the surface, so that if possible a boring might be made 
on the spot. The results were encouraging, but the conditions were such that the 
lagoon-boring had to be made elsewhere. It will be obvious, though, that any future 
boring should be preceded by a proper magnetic survey of the atoll selected. 
On the afternoon of the same day we sighted Farquhar, passing round on the west 
side of its reefs to our anchorage just outside the passage round the west point of North 
Island. The bank has no land to the south-west, and of six little islands to the north- 
west which existed in 1878, only three are now found, the others having been gradually 
swept away. ‘To the south-west we saw upon the reef the wreck of the ‘ Hardwick Hall,’ — 
and to the north-west that of the ‘ Aymestry, two fine steamers, victims probably of 
the strong currents or of the peculiar variation in this part of the ocean. To the 
north-west we passed over a shallow bank, where the 100-fathom line extends out for four 
or five miles from the surface-reef. We had leadsmen in the chains, and for three miles 
the bottom, varying from 7 to 12 fathoms in depth, was clearly visible. It appeared to 
consist almost entirely of bare white sand or mud, with patches of weed and soft corals, 
only one clump of true reef-building coral being seen at a depth of 47 feet as we passed 
off its northern edge. 
We remained at Farquhar for three days, during two of which Cooper with 
Mr. Alexander went to examine and to run a section of South Island, while Gardiner 
ran a section off the reef to the north and examined North Island. The third day we 
* These facts illustrate the value of such observations to navigation, The variation also changes slightly year by 
year, and probably it would repay maritime nations to employ vessels constantly on this work. 
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