52 MEMOIRS of the 
to fignify the degree of heat in the air, cannot be underflood, 
unlefs by thofe, who have thermometers of the fame make and 
adjuftment^ much lefs has the way been fhewn how to make this 
inftrumcnt without a ftandard, or to make two of them agree 
artificially, without comparing them together : To this Mr. Halley 
fabjoins, that whereas the ufual thermometers with fpiritsof wine, 
do fome of them begin their degrees from a point, which is that 
at which the fpirits ftand, when it is lb cold as to freeze oil of 
anifeed ; and others again, from the point of beginning to freeze 
water; Mr. Halley conceives thofe points not to be fo juftly 
determinable, but with a confiderable latitude 5 and that the juft 
beginning of the degrees of heat and cold fliould not be from liich 
a point as freezes, bui: rather from temperature, fuch as is in places 
of confiderable depth under ground ; where the heat of the fummer, 
or cold of winter, have, by the experiment of M. Mariotte-, in the 
grotto's under the obfervatory at ^aris, been found to have no 
manner of effef^. 
Some farther Conjidcrations on the Breflaw Bills of Mortality 5 
by Mr. Edm. Halley. Phil. Tranf. N° 198. p. 554. 
MR. Halley endeavoured to find out a theorem, that. might 
be more concile than the rules laid down N° 1^6. p. 596'. 
for computing the value of two, three, or more lives, but all in 
vain; for all that can be done to expedite it, is by tables of loga- 
rithms ready computed, to exhibit the ratio's of N to Y in each 
iinglelife, for every third, fourth, or fifth year of age, as occafion 
Ihall require 3 and thcfe logarithms being added to thofe of the 
j)relent value of money payable after fo many years, will give a 
ieries of numbers, the ibm of which will Ihew the value of the 
annuity fought; however, for each number of this feries, two 
logarithms for a fingle life, three for two lives, and four for three 
lives muffc necefTarily be added together. 
It may not perhaps be unacceptable to infer from the tables, 
K° i()6. how unjuftly we repine at the ihortnefs of our lives, 
and think ourfelves injured, if we attain not to old age 5 
whereas hereby it appears, that the one half of thole that 
are born, are dead in feventeen years time, 1238 being in 
that time reduced to 616 -j 1^o that inftead of murmuring at 
what we call an untimely death, we ought to account it, as a 
bleffing that we have lurvived, perhaps" by many years, that 
period of life, at which the one half of the whole race 
of mankind doth not arrive: A lecond obfervation is, that 
the growth and encrcafe of mankind is not fo much Hinted 
by 
