Prefranked envelope posted from KESRIE-(ΚΑSTORΙΑ) and destined to ISTANBUL-(CONSTANTINOPLE) 1841. Postal rate: 3 kurus and 30 para [left: (3x40pa)+30pa=150pa=3 kurus and 30 para, because 1 kurus=40 para]. The weight of the envelope was 3 dram. Kastoria was on the way number 2 to Constantinople,155 hours away. The postal rates during the prefranked period were estimated according to a system, which was based on the distance (from already given lists). In this way, we had for every one hour distance and for envelope weight 3 dram postal rate 1pa. Every extra dram was charged with 0.5pa for every one-hour distance. So, at this point, the postal rate is correct ( 1x150 hours=150para).