52 THE VOYAGE OF H.M.S. CHALLENGER. 



(see Sheet 4). At 8 p.m., when between the Dezertas and Madeira, the trawl was put 

 over, it being too dark to continue sounding during the night ; but at 2.30 A.M. on the 3rd, 

 the trawl fouled something at the bottom, and the rope parted at 6 a.m., after four hours 

 tedious labour in endeavouring to recover it. The ground being evidently unfit for 

 trawling at this place, sounding operations were resumed towards Madeira, and were 

 completed by 11 a.m., at which hour the anchor was let go in Funchal Bay. The 

 deposits about the Dezertas and Madeira were volcanic sand and mud, with usually 30 

 to 40 per cent, of carbonate of lime. The mineral particles in the deposits were frag- 

 ments of felspar, magnetite, lapilli, basaltic scoriae, and glassy fragments. 



At Madeira magnetic observations were taken at three places : (l) on the highest part 

 of the rocky cliff forming the first point west of Pontinha Fort, after crossing the bridge 

 over the valley, on some waste ground close on the seaward side of, and rising a little 

 above, the main road, immediately opposite a garden gateway, in a wall on the opposite 

 side of the road ; (2) in Fort Pontinha ; and (3) on the small almeida on the eastern side 

 of the above mentioned bridge. 



Tenerife. 



On the 5th the ship left Madeira for Tenerife, arriving at that island on the 7th, 

 one sounding having been obtained on the passage (see Sheet 2). On the way from 

 Madeira to Tenerife a very strong N.E. trade wind was experienced, which prevented 

 dredging or any other deep-sea work at or near the Salvage Islands. Immediately 

 after the ship anchored at Santa Cruz, a salute of 20 guns was fired from the shore, 

 and on inquiry it was found to be in honour of a son born to King Amadeo, who by 

 that date had abdicated the throne and left Spain. 



The anchorage off the town of Santa Cruz being imperfectly known, the per- 

 mission of the Governor of Tenerife was obtained to resurvey it, and that work was 

 commenced at once. The usual magnetic observations were taken on a circular 

 enlargement of the main road to Laguna outside the town south of the first bridge. 

 The observations for rating chronometers were taken in Fort San Pedro, and during 

 the operations it was noticed that the mercury in the artificial horizon occasionally 

 vibrated considerably for a few seconds, without there being any apparent reason for its 

 doing so. Whether this arose from seismic action or not is uncertain ; it clearly did not 

 arise from the movements of carts, or men in the vicinity, especially as it occurred 

 in the afternoon, when every one on shore was enjoying the usual siesta. 



On the 10th the ship left the anchorage at Santa Cruz for a sounding and dredging 

 excursion round the island, obtaining twelve soundings and two dredgings (see Sheet 5). 

 The weather was remarkably fine, and the Peak of Tenerife, capped with snow, distinctly 

 visible. 



