1 If the two places differ only in Latitude, and lie vnder the
same Meridian if the places lie both on one side of the Æquator,
the differences of the latitudes: or the summe of both latitudes
added together, if one place lie North and another South, being
turned into Miles giues the true distance.
2 If the places differ only in Longitude, and lie both vnder one
paralell of latitude the difference of longitude turned into
miles proportionably accordinge to the latitude of the paralell,
giues the true distance.
3 The distance of places differing both in latitude and longitude
may thus bee found out, first let there bee drawne a semicircle
vpon a right diameter noted with (_ABCD_) whereof (_D_) shall bee
the Center. The greater this Semi-circle is made, so much the
more easie will bee the operation; because the degrees will bee
larger. Then this Semicircle being drawne, and accordingly
devided, imagine that by the helpe of it, you desire to find out
the distance betwixt London and Ierusalem, which Citties are
knowne to differ both in longitude & latitude. Now, that the true
distance betwixt these two places may be found out, you must
first substract the lesser longitude out of the greater, so shall
you find the differences of their longitudes, which is 47.
degrees. Then reckon that difference vp[~o] the Semi-circle,
beginning at (_A_) & so proceed to (_B_;) & at the end of that
difference, make a marke with the leter (_E_) vnto which point by
your ruler, let a right line be drawne from (_D_) the center of
the Semi circle. This being in this sort performed, let the
lesser latitude be sought out which in 32 degrees, in the fore
said semicircle, beginning your accompt from the point (_E_) and
so proceede towards (_B_), and at the end of the lesser latitude
let another point be marked out with the letter (_G_), from which
point, let there be drawen a perpendicular line which may fall
with right Angles vpon the former line drawen from (_D_) to
(_E_), and where it chanceth to fall, there marke out a point
with the letter (_H_): This being performed let the greater
latitude which is 51 degrees 32 minuts, be sought out in the
semicircle beginning to reckon from (_A_) towards (_B_) and at
the end of that latitude set another point signed out by the
letter (_I_) from whence let there be drawen another
perpendicular line that may fall with right angles vpon the
diameter (_AC_): & here marke out a point with the letter (_K_),
this done take with your compasse the distance betwixt (_K_) and
(_H_) which distance you must set downe vpon the diameter (_AC_)
placeing the one foot of your compasse vpon (_K_) and the other
towards the center (_D_) and there marke out a point with the
letter (_L_); then with your compasse take the shorter
perpendicular line (_GH_,) and apply that widenesse vpon the
longer perpendicular line (_IK_,) placing the one foote of your
compasse at (_I_,) which is the bounds of the greater latitude,
and extend the other towards (_K_), and there make a point at
(_M_), then with your compasse take the distance betwixt (_L_)
and (_M_), and apply the same to the semicircle. Placing the one
foot of your compasse in (_A_) and the other towards (_B_), &
there marke out a point with the letter (_N_), now the number of
degrees comprehended betwixt (_A_) and (_N_) will expresse the
true distance of the two places, which will bee found to be 39
degrees: which being multiplied by 60. and so converted into
miles according to the former rules, will produce 2340. which is
the distance of the said places.