ike Gbfervations of Mr. Hoo\ made in February and March h$ s 
and by him communicated to the 7 {oyal Society , and fince 
Printed in theTrtfw/k^ow/.publifhed Jpr.i. 1666. confonant 
to the hke obfervations vt Jupiter, made by him in May 1664., 
and fince communicated .to the fame Society ; and then pub- 
tifhed in the TranfaUmit, of March. £ then next follow- 
ing. Now that the Earth hath fiich a motion about its own 
Axis ( whereby it might be fitted to carry about the Moon ) 
is evident by its Diurnal motion. And it feems as evident that 
the Moon hath not > becaufe of the fata e fide of the Moon ah 
waies turned towards us ; which could not be * if the Moon 
carried the Earth about : UnlefFe we fhould fay, that it carries 
about the Earth in juft the fame Period, in which it turnes up- 
on its own Axis; Which iscontrary to that of the Sun carry- 
ing about the Planets : the fhorteft of whofe Periods , is yet 
longer than that of the Suns moving about its own Axis. And 
the like of Jupiter, fliorter than the Period of any of his Satelli- 
tes ; if at leaft the Period of his con verfion about his Axis, late- 
ly faid to be obferved, prove true. ( Qf Saturn we have not 
yet any Period affigned ; but it’s likely to be fhbrter, than that 
of his Sate lies. ) And therefore we have reafon to believe, 
not that by the Moons motion about its Axis the Earth fhould 
be carried by a contemporary Period ( whereby the fame face 
of the Moon fhould be ever towards us * ) butthat by the Eahhs 
revolution abouts its Axis in 24. hours, the Moon fhould be 
carried about it in about 39. dayes, without any motion on its 
own Axis : And accordingly, that the Secondary Planets about 
Jupiter and Saturn , are not ( like their Principals ) turned a- 
botit their own Axis. And therefore I am not at all inclined 
to believe, that the Menjlrual Period of the Tides with us is to 
befalved by fuch an Hypothefis. 5 
In ftead of this, that Surmife of mine, (for I dare not yet, 
with confidence g ve it any better name, ) of what I have fpok- 
en to you heretofore, ( and which hath occafioned this^pre- 
fent account which I am noW'giving you, ) is to this purpofe. 
The Earth and Moon being kno wn to be Bodies of fo great 
connexion ( whether by any Magnetick; or what other Tye, 
I will not determine j nor need I, as to this purpofe j ) as that 
O o the 
