so .. ASTRONOMICAL AND 
Bus COM Table of the Equations to equal Altitudes, for the’ La- 
> fitude of the Univerfity of Cambridge, 42*23' 28" N: with 
"^an Account of it’s Conftruétion and’ Ufe. By the Reverend 
| Josse WirrAkb, posee T p Oniverfity. 
KLE regulation-of a clock, .which .is made ute of for 
ad -saftrenomicsl PEPR. is of the. ntmoft. importance. 
-Unlefsit's going : ícertained, the obíervations made 
by it, however wiat; in reme ‘refpedts, can be: of no ufe. 
Every thing, therefore, which tends to facilitate it's regulation, 
is worthy of attention. 
The beft ded to Mein the going of a clock, where a 
` perfon has not a tranfit inftrument fixed in the meridian, is by 
equal altitudes of the fun, taken by fome inftrument adapted. 
to the purpofe. Hadley's Sec is. the moft eafily obtained ; 
and double altitudes may betak nby i it, by reflection from a 
bowl of- fome liquid, which: will i not be eafily put into motion 
by the air. The oil of tar, -or very clean molafles will anfwer 
the purpofe well. 
~ The method is, to take the altitude of the fun’s upper or 
lower limb, or both, in the morning as far trom noon as may 
- . be convenient, and note the time by the clock to a fecond. 
"The time muft be noted in the afternoon, when the altitude i is 
the fame. Then, add half the interval between the two obfer- 
. Vations, to the time of the morning obfervation, which. wil 
give the time ix the clock, nearly, when the fun's center paffed 
the 
= RE SM gla Vi d Tato 
