VOL. XV.] PHILOSOPHICAL TRANSACTIONS. I3g 



Flint 2542 Block tin 7321 



Glass of a quart bottle 2666 Copper 8843 



Black Italian marble 2704 Lead 1 1345 



White Italian marble 2707 Quicksilver 1 4019 



Another sort, closer texture 2718 Another sort 13593 



The last experiment was tried with another quantity of quicksilver, which 

 had been used in water in the preceding experiment, and this last is more to be 

 depended on; as a small mistake, though here in the calculation allowed for, was 

 found in the weight of the glass containing the quicksilver in the preceding 

 trial. 



The solids here mentioned were examined hydrostatically, by weighing them 

 in air and water; but the fluids by weighing an equal portion of each in a glass 

 holding about a quart. The numbers show the proportion of gravity of equal 

 portions or bulk of these bodies. So that knowing by the former table, the 

 weight of a cubic foot of water, and by this, the proportion in gravity between 

 water and alabaster, we may by the rule of three find the* weight of a cubic foot 

 of alabaster; and the same of any other of these bodies ; or we may know their 

 magnitude by knowing their gravity. So that an irregular piece or quantity of 

 these bodies being offered, by weighing them, we may know their just magni- 

 tude without further trouble. 



^ Letter from Dr. Robert Plott, of Oxford, to Dr. Martin Lister, F. R. S. 

 concerning the Use which may be made of the following History of the fVeather, 

 made by him at Oxford throughout the Year l684. N° 1 69, p. QSO. 



This register of the barometer is by a new and easy invention of observing 

 the rise and fall of the mercury in the barometer, by parallel lines drawn from 

 every decimal part of each month of its whole extent, marked by the wander- 

 ing pricked line in the figure belonging to each month, like a map as invented 

 by Dr. Lister. In a printed list for every day in the year, is set down the cor- 

 responding state of the weather, as to the quarters of the wind, E. W. N. and 

 S. also as to the rain or fair weather, frost or snow, &c. 



This practice is here recommended, as likely to be attended with many be- 

 neficial efl^ects, observing that, by this means it is doubtless, that the learned 

 Dr. Goad of London has arrived to such a pitch of knowledge in predicting 

 weather, &c. i. e. by making such old almanacs as this for many years instead of 

 new ones, which if once faithfully done in divers parts of the world, we should 

 certainly obtain more real and useful knowledge in these matters in a few years 

 than we have yet arrived to in many centuries; which was doubtless the opinion 

 of the industrious Walter Merle, Fellow of Merton College, who thus ob- 



