 Thus, there was a period of 47 years, from 1815 to 1862, with no presidential  prayer proclamations.
<meaning-changed>  Thus, there was a period of 47 years, from 1815 to 1862, with no presidential  prayer proclamations.
 Thus, there was a period of 47 years, from 1815 to 1862, with no presidential public prayer proclamations.