Royal Society. 71 
to it a very finall liar, which the Arabi call Akor, a.nd which 
Hevelius in his obfervations finds to be diftant from it about 9' 
and 5 or 10" ; fo that befides the advantage of dilcoverincr the 
parallax of the greater ftar, if difcernible 5 the difference of pa- 
rallax of that and of the leffer ftar, being both within the reach 
of a micrometer, may do our buiinefs as well 5 for if that of the 
greater ftar be difcernible, but that of the lefler, either not dil^ 
cernible or lefs difcernible, their different diftances from each 
other at different times of the year, may, perhaps, without far- 
ther apparatus-t be dilcerned by a good telefcope of a competent 
length, furnilhed with a micrometer, if carefully preferved from 
being difordered in the intervals of the obfervations 5 and diicover 
at once, both that there is a parallax, and that the fixt ftars are 
at different diftances from us 3 wherein his meaning is not that 
the inftrument or micrometer fliould be removed for the obierving 
of the leffer ftar, but that, when the azimuth of the greater ftar 
is taken, by a micrometer coniifting of feveral fine threads paral- 
lel and tranfverle, may at the lame time be oblerved the diftance 
of the two ftars from each other, in that pofition, both being at 
once within the reach of the micrometer 3 which diftance, the in- 
ftrument remaining unmoved, if it be found, at difeent times 
of the year, not to be the fame, this Vv^ill prove that there is a 
different parallax of thefe two ftars : This latter part of the ob- 
lervation, of their different diftances at different times, he fug- 
gefts as more eafily pra6iicable, tho' not fo nice as the former 5 for 
it may be done, he thinks, without any farther apparatus there 
than a good telelcope of ordinary form, furnilhed with a micro- 
meter, which is carefully kept unvaried during the interval of 
thefe obfervations 5 and if this part only of the obfcrvation, 
^Avithout the other, be purfued, it matters not tho' the two ob- 
fervations near the two Iclftices be, one at the eaftern, the other 
at the weftern azimuth, whereby both may be taken in the night 
time 3 for the diftance muft at both azimuths be the Ume^ if, af- 
ter obierving the azimuth of the greater ftar, it be r.vceilary to 
move the micrometer for meafuring its diftance from Akor^ that 
may be done another night, and it is not neceffiry to be done at 
one obfervation, for that diftance cannot be diicernibiy varied in 
a nighc or two. 
Obferv.^tions on the Animalcula /';; Pepper-water, ^c. hy Sir 
Edm. King. Phil. Tranf. ]S!° 203. p. Sdi. 
HAving fteeped oats in rain-water for Ibme days, and viewing 
it with the naked eye, a fubftance was oblerved, refem- 
bling what is ufually called a mother on other liquors, and lay- 
