Dionysius
2 of the 7 encyclopedias on this shelf carry an entry for Dionysius. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
a historian and critic of Halicarnassus, in Caria, who was invited to Rome about 30 b. c., and there wrote his "Roman Antiquities" Other works DIOSCOREACEÆ are "De Compositione Verborum," and the "Structure of Language." Lived in the 1st century, dying about 7 B. C. DIONYSIUS I., the Elder, tryant of Syracuse; was born 430 b. c. He served in the war with the Carthaginians, got himself appointed general, and, in 405, sole emperor and head of the republic. He formed a powerful bodyguard, conquered other cities of Sicily, carried on war with the Carthaginians, and after making peace with them in 392, invaded Italy and subdued several of the Greek cities of the south. He was afterward again at war with Carthage. Dionysius, like some other tyrants, was a patron of literary men and artists, aspired to literary fame, and contended for the prize at the Olympic games. He erected many fine temples. He died in 367. DIONYSIUS II., the Younger, tyrant of Syracuse, was son of the preceding, and succeeded him, 367 b. c. Idly brought up, he was for a time restrained from excesses by the influence of Dion and Plato. His subsequent treatment of Dion and his family led to his own overthrow in 356. He went to Italy and obtained the chief power at Locri, and after 10 years' absence returned and regained his throne at Syracuse. A final end was put to his tyranny by the noble Greek Timoleon, 343, and he spent the rest of his life in exile at Corinth.
Aiton's Encyclopedia (1910)
di-o-nish'i-us (431 or 430-367 B. C.), the tyrant of Syracuse. Originally a clerk, he succeeded in having himself appointed to a military command, which he managed in such a way as to make himself absolute master of the city. He was a ruler of ability, maintaining himself against the Carthaginians with skill. He made Syracuse an important commercial factor in the Mediterranean Sea and subdued his neighbors on the adjacent coasts of Italy. He aimed also to attract attention in the Olympian games, and contended several times for the prize for tragedy at Athens, winning third and even second, but never first place. He is remembered for the construction of a state prison in the form of a whispering gallery. It was known as the Ear of Dionysius. By placing himself at the end of a tube leading from the cell, he was able to overhear the slightest whispers of his prisoners as they conversed. In this way, he sought to keep himself informed of the plots and stratagems that surround a king, especially one who has seized authority by force of arms. Among the whims of this monarch was a stand carrying as many lamps as there are days in the year. See Damon; Damocles ; Syracuse