Encyclopedias are great for:
Specialized Antiquity Encyclopedias
Oxford Handbook of Engineering and Technology in the Classical World Highly recommended.
The Oxford classical dictionary. A classic on the Classical world. It goes far beyond a dictionary.
Oxford bibliographies: Classics Peer-reviewed annotated bibliographies.
History of Science & Technology Encyclopedias
The Routledge companion to philosophy of science (Uris Library Q175 .R68 2008)
The encyclopedia of ancient natural scientists: the Greek tradition and its many heirs. (2nd ed., 2012) Covers all Greek and Latin natural science, from its beginnings with Thales through the end of the Late Antiquity with Isidore of Seville and Paulos of Aigina. Almost 1600 entries - 244 of those describing figures that are not mentioned in any other reference work. (Olin Reference Q124.95 .E53 2012)
Encyclopaedia of the history of science, technology, and medicine in non-western cultures (Olin Library Oversize Q124.8 .E53x 1997 +)