58 



REPORT — 1861. 



126, at Ban-ahead, in the Hebrides ; and this appears the more remarkable, S the 

 neighbouring lighthouse at SkeiTyvore retm-ns the very low number of 6 days ; but 

 the Skerryvore is a low rock many miles fi-om land, while the station at Ban-ahead 

 is the highest in the United Kingdom, on the southernmost point of a range of 

 large islands, and near the Gulf-sti-eam. The eastern side of the Hebrides is not 

 foggy. The southernmost point of the Shetland Islands likewise returns a high 

 number. The smallest number noted is at Troon in AjTshu-e, viz. 4. 



6th. Where a large area of sea is sun-ounded on most s'des by land, fogs are 

 infrequent — at least this seems to hold good on the coasts of the Moray Firth, the 

 Minch, the Fu-th of Clyde and neighbouring sea, the Solway Firth, and Donegal 

 and Sligo Bays. It is otherwise in the Bristol Channel. The Irish shore of St. 

 George's Channel retiu-ns also small numbers, except at Dublin Bay. 



0)1 a Deep-Sea Thermometer invented hy Henry Johnson, Esq., 39 Crutched 

 Friars. By James Glaisher, F.R.S. 



The deep-sea thermometer is intended to be used in expei-iments made with the 

 deep-sea pressui-e-gauge, to ascertain how much of the variation in volimie indicated 

 by the gauge is caused by variation of temperature. 



In several experiments made by Mr. Glaisher in the year 1844 upon the tempe- 

 rature of the Thames water, at difterent seasons of the year, it was found that the 

 indications of temperatm-e were very materially affected by the pressure of water 

 upon the bidbs of the thermometers used, even at the depth of 25 feet. 



This circmnstance demonsti-ated the importance of a thermometer for deep sotmd- 

 ings without liability to derangement of indication fi-om pressiu-e of water, and led 



A. The cyUnder. B. Stem with graduated scale. C. Flat elastic ring or index. 



D. Elastic stopper. E. Metal frame lined with caoutchouc. 



P. Caoutchouc rings protecting glass gauge from concussion. 



G. Caoutchouc rings, in the'case, securing gauge in position. 



H. Metal hook in the door of ease securing the top. 



I. Clasp to door, let in to avoid projection. 



K. Vent, or grooved needle inserted with stopper. 



L. Brass hook to draw up needles. 



