Secondary evidence means and includes—

1. certified copies given under the provisions hereinafter contained;
2. copies made from the original by mechanical processes which in themselves ensure the accuracy of the copy, and copies compared with such copies;
3. copies made from or compared with the original;
4. counterparts of documents as against the parties who did not execute them;
5. oral accounts of the contents of a document given by some person who has himself seen it;
6. oral admissions;
7. written admissions;
8. evidence of a person who has examined a document, the original of which consists of numerous accounts or other documents which cannot conveniently be examined in Court, and who is skilled in the examination of such documents.