This unusual gravestone memorializes a Doctor of Medicine and more specifically a surgeon. The acronym F.R.C.S. denotes that the deceased earned a professional qualification to practise as a senior surgeon in Ireland or the United Kingdom. An additional acronym, F.R.C.S. c, identifies the Fellowship of the Royal Colleges of Surgeons of Canada.
The symbolic engraving is related to astrology and is known as a natal chart. The chart is 360°, the 12 zodiac signs are 30° each and the relationships (aspects) shared between the planets in the chart is determined by the distance of the signs they are in.
If you are interested in astrology you may wish to click on the link below which, although identified as a chart for beginners, was beyond my comprehension and interest.