A great introduction to Russian postmarks of this period is "Russian Postmarks, an Introduction & Guide" by A.V. Kiryushkin & P.E. Robinson.
In this is noted that the St. Petersburg circle numeral cancellations were introduced in 1880. Each sub-office had a distinct inside shape such as squares, triangles etc. allowing each to be identified even if the number was illegible.
St. Petersburg circle numeral cancellations

In the 1870's Moscow sub-offices started using OVAL numerical cancellations, which is what we have on the above cover.
Moscow oval numerical cancellations

These numerical cancellations were used only to cancel stamps while in 1860 circular datestamps were introduced. In the 1880's an attempt was made to standardise Russian postmarks with post-horns in the lower part, the example here being one of them.
Moscow circle postmark

The postmark on the cover reads -
Moscow - 29 November - 1889 - 2 (o'clock) - Posthorn (obscured by writing) On the left of the post-horn is the Russian letter "G", on the right "P", "Gorodskaya Pochta" (Town Post)
I'm afraid my Russian script reading is poor & I can't make out any of the address.