55 
restoring the Action of the Lungs . 
■tet at a temperature sufficient to maintain the air propelled into 
the lungs at the usual animal temperature , of 98° Fahr. E 
represents a thermometer for more accurate adjustment, and F, a 
pipe communicating with the interior cylinder, and to which the 
flexible tube is attached. 
Art. X.— Account of the Rousts or Currents of Tide m the 
Pentland Frith , 3fC. from the Manuscript Journal of the 
late Reverend George Low of Orkney. With Preliminary 
Observations by Samuel Hibbert, M. D. F. R. S. E. &c. &c. 
F here are probably no natural phenomena incidental to the 
islands of the North of Scotland, that have more attracted the 
attention of the few naturalists who have visited this remote dis- 
trict of Britain, than the various and opposite directions of the 
tides. There is, for instance, bearing off the most southerly ex- 
tremity of Shetland, named Sumburgh Head, what is termed 
in the provincial phrase of the country, a roust, — this being a 
word of Scandinavian origin, used to signify a strong tumultu- 
ous current, occasioned by the meeting of rapid tides When 
the sea is calm, there is the appearance of a turbulent stream 
of tide, about two or three miles broad, in the midst of smooth 
water, extending a short distance from Sumburgh, and then 
gradually dwindling away, so as to terminate in a long slender 
dark line, bearing towards Fair-Isle. I believe that appearances 
like these have generally met with less attention than is due to 
their importance, and the investigation of them may, perhaps, 
be satisfactorily prosecuted in reference to the concise statement 
which has been given by Mr Playfair, of the causes of the Bri- 
tish tides that are propagated from the great diurnal undula- 
tions of the Atlantic. 44 The high water transmitted from the 
tide in the Atlantic,” says this author, 44 reaches Ushant be- 
tween three and four hours after the moon has passed the meri- 
dian, and its ridge stretches N. W., so as to fall a little south 
* Id. roest , raust , sestuaria, vortices maris, Verel, Ind. Supposed by one au- 
thor to be synonimous with the A. S. rase , stridor, impetus fluvii.— See Jamieson’® 
Etym. Diet, word roust. 
