אוצר דינים ומנהגים / A Digest of Jewish Laws and Customs - By J. D. Eisenstein, copyright 1917, printed in 1938.

  Rabbi Eisenstein was a compiler of anthologies and encyclopaedias on Jewish topics, most famously his Otzar Yisrael, the first Jewish encyclopaedia in Hebrew. He was a strong advocate of Orthodox Judaism in America in the late 19th and early 20th centuries. His son married Mordecai Kaplan’s daughter. 
Julius (Judah David) Eisenstein (November 12, 1854 – May 17, 1956) (Hebrew: יהודה דוד אייזנשטיין‎) was a Polish-Jewish-American anthologist, diarist, encyclopedist, Hebraist, historian, philanthropist, and Orthodox polemicist born in Międzyrzec Podlaski (known in Yiddish as Mezritch d’Lita), a town with a large Jewish majority in what was then Congress Poland. He died in New York City at the age of 101.
 
Eisenstein was a scholar of extraordinarily broad learning. He contributed more than 150 entries to the 1901–1906 Jewish Encyclopedia, from which much of the above biography was based, and he authored thousands of articles in newspapers, journals, encyclopedias, and anthologies.
His memories are contained in a 1929 volume called Otzar Zikhronotai (אוצר זיכרונותי).
Other works, most of which can be downloaded at HebrewBooks.org are as follows:

Otzar Perushim we-Ziyurim (1920) (אוצר פירושים וציורים להגדה של פסח), an illustrated Passover haggadah
Otzar Dinim u-Minhagim (1917) (אוצר דינים ומנהגים), a digest of Jewish laws (halakha) and customs (minhagim)
Otzar D’rushim Nibharim (1918) (אוצר דרושים נבחרים), an anthology of midrashic literature
Otzar Maamare Hazal (1922) (אוצר מאמרי חז”ל), a concordance of rabbinical quotations, sayings and phrases
Otzar Ma’amare Tanakh (1925) (אוצר מאמרי התנ”ך), a concordance of words, phrases and idioms in the Tanakh
Otzar Masa’oth (1927) (אוצר מסעות), an anthology of itineraries by Jewish travelers to Palestine, Syria, Egypt, and other countries
Otzar Midrashim (1915) (אוצר מדרשים), “Anthology of Midrashim,” a library of 200 minor midrashim
Otzar Vikukhim (1922) (אוצר ויכוחים), “Anthology of Debates,” a collection of polemics and disputations with Christianity
Otzar Yisrael (principal editor, 1906–1913, 10 volumes) (אנציקלופדיה אוצר ישראל), which has the distinction of being the first comprehensive (i.e., not restricted exclusively to Jewish topics) encyclopedia in the Hebrew language. Eisenstein undertook this work in response to perceived limitations of the English-language Jewish Encyclopedia.[4]

For obvious reasons, he was known by many colleagues as the Ba’al ha-Otzrot (“Master of the Anthologies”). His works remain standard reference books in yeshivot, batei midrash, synagogues, and Jewish libraries to this day.