Today in Postal History

This folded letter went from Hong Kong to Karachi
(note the 1873 spelling of Kurrachee) by way of Bombay.
The letter would have been put on a mail ship bound for Bombay
where it probably would have gone overland by rail to Karachi.

Karachi is now part of Pakistan.
It is a major port on the Indian Ocean.

There are three postal marks associated with Hong Kong.
The first is the numeral cancel used on the stamp itself.
The second is the CDS on the reverse.
The third is a CDS-like mark which was from the sender in Hong Kong.
An expanded view of the mark shows a 'Co.' just at the end of a line extended to the right from the 7.
I am not certain of the use of the straight line OOLxx on the reverse.*

There is also a Bombay transit mark on the reverse but the July date is obscured.
It arrived in Karachi on July 8.

The letter is franked with a wing copy of the 8c. pale dull orange Victoria issued in 1864 (SG 11).

*David Benson suggests that the straight line marking may be a TOO LATE
associated with the posting and sailing times.
He also suggested that the second Hong Kong marking could be from the sender.
This has proven to be the case upon closer examination.