An enquiry into the natural history, cehmical properties, and medical virtues, of the rock oil, or green mineral naphtha, of Barbados : particularising the successful experiments ... observations on digestion ... / by C.H. Wilkinson.

Wilkinson, C. H. (Charles Henry)

Date:: 1830

Credit: An enquiry into the natural history, cehmical properties, and medical virtues, of the rock oil, or green mineral naphtha, of Barbados : particularising the successful experiments ... observations on digestion ... / by C.H. Wilkinson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

18/90 (page 6)

$0 suddenly, ami rose more than two feet higher than the highest spring tides, and in three minutes ebbed to be as much lower than the usual lowest ebb, and then again as high as before, and continued to rise and fall every five minutes. It commenced at 20 minutes aller two at noon, slowly diminishing almost in arithmetical progression, after the first four or five impulses, till near seven in the evening. About nine, the return of the usual tide checked the oscil- lation. These phenomena occurred on the same day that the dreadful earthquake at Lisbon took place. The first alarming shock was felt at Lisbon at 45 minutes after nine in the morning, and the second agitation at 20 minutes after ten. Presuming that they both arose from the same disturbing cause, it becomes easy to calculate the velocity of this movement: the distance between Lisbon and Bridgetown is .‘3,400 English miles, and the difference of longitude equal to hours, which, being added to the difference of time of observation, will make it seven hours and a half, or after the rate of nearly 7{ miles each minute. During the whole of this great disturbance the barometer evinced only TV of an inch in variation. Ever since the period of Galileo and his pupil Torricellius, and the expe- riments of Paschal, it has been generally supposed that the barometrical variation depends on certain alterations in the weight of the atmospheric mass. We are indebted to K. Saumarez, Esq. of the Circus, Bath, for a series of valuable observations, illustrated by experiments, from which he has rationally deduced, that, under no conditions, is there any variation in the atmospheric column in the same place, and the difference in height of the mercury depends on the change of pressure as to its expansibility, and not as to any positive weight. This opinion is power- fully supported by the meteorological fact above stated, that, in all the variety of atmospheric disturbance at Barbadoes, the variation of the barometer never exceeded ^ of an$