The letters which are intended to form the chronogram are:
C I C V I I L D M I V
100 1 100 5 1 1 50 500 1000 1 5
These figures added together total 1764.
The second inscription on the clock dial which forms a chronogram is
LaVs saCrosanCtae TrIaDI VnI Deo, et DeIparae
L V C C I D I V I D D I
50 5 100 100 1 500 1 5 1 500 500 1 = 1764.
The third inscription required a little more planning, because of its greater length. Accordingly, Father Borghesi divided it into nine parts, each of which is separated from the other by means of asterisks. Each of the nine parts of the inscription formed a chronogram which, in every instance, totals to the date 1764, the year in which the second clock was completed. The same procedure was followed with the inscriptions in the lower left and the lower right corners of the dial as well as with the maker's inscription within the central disk. This inscription is
BVrghesIo DoCtore, et BertoLLa LIMatore AnnanIensIbVs
V I D C L L L I M I I V
5 1 500 100 50 50 50 1 1000 1 1 5 = 1764.
The inscriptions within the chapter ring are not utilized for chronograms, however. It is apparent that Father Borghesi was required to make a most careful selection of the texts for his inscriptions in order that none of the phrases included any additional letters which formed Roman numerals than would total to the date he desired to indicate, namely, 1764. Where it was necessary, he employed an asterisk to separate parts of texts so that each would produce the same total. Any letter that did not form a Roman numeral, even if capitalized or used in a larger size, did not interfere with the formation of the chronograms.
In spite of his ingenuity in designing a text which would include only such of the letters representing the Roman numerals which would provide the chronograms for 1764, Father Borghesi experienced some difficulties, particularly in place names. He accordingly changed them in order to avoid the inclusion of letters that would have disturbed his totals. Examples are MEGGL instead of MECHL, which had an extra C, and RVNNO instead of RVMO, which had an extra M.