Tiers of shining casements

[Xinfu]

http://www.freeenglish.jp/holmes/en/redc-en-006.html
The light had suddenly gone out, the glimmering square of window had disappeared, and the third floor formed a dark band round the lofty building, with its tiers of shining casements.

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My interpretation:
-The third floor is dark, but other floors contain casements (=windows), which are shining because people there are using lamps.

Do you agree?

[Rusty]

The only light on the third floor had gone out. The other floors are still lit, hence the shining casements on those floors.

[Xinfu]

Thank you~