Take a look at the maps.
The first pair of maps shows part of Troedyrhiw as recorded on the 1850 tithe map of the Merthyr area side-by-side with a modern street map. Note Pontyrhun Bridge on the left and what we think is the FIRST Saron Chapel (built 1835) indicated by the number 981. The area of the Saron site (chapel + graveyard) at this time was given as 10 P which, we think, means 10 square poles or roughly 302 sq yd. Compare this with the other image (below) which shows that the SECOND Saron Chapel (built 1852) occupied an area approximately 7 times larger (chapel + vestry + cottages + graveyard + common area for WC’s etc).