Marmaduke Marcelus Michael Slattery (1851-1892) was an engineer who contributed to lighting systems in the early days of the incandescent lamp. Much of what is known about Slattery's working career can be gleaned from Linkous' book3. The Linkous book is a well-researched history and the writer will take advantage of it to present this brief write-up.
Slattery was born in Ireland and his first work in the electrical field took place in London. After a few years in that capacity he emigrated to New York City and began to work for the United States Electric Lighting Company. He was in New York by the year 1883. He worked next for the Sun Manufacturing Company of Massachusetts. While employed there he was granted U. S. Patent No. 358,492, on Mar 1, 1887, for a sealing-in process. In that same year he traveled to Fort Wayne, Indiana in order to work for the Fort Wayne Electric Light Company.
Linkous said3: "A full line of electrical products were marketed by FWELC under the banner of the 'Slattery System.' His greatest achievement was the development of a constant voltage, alternating current, incandescent lamp lighting system." Later his systems were replaced by those developed by James John Wood.
A magazine advertisement from about 1888, as scanned from the Linkous book, is shown below.
M. M. M. Slattery passed away on Dec 14, 1892 from hemorrhage of the lungs. For additional details of Slattery's life it is recommended that the Linkous book be consulted.
References
1) Obituary - Marmaduke M. M. Slattery, The Electrical Engineer, Vol XIV, No 242, Dec 21, 1892, pg 607.
2) Photograph of M. M. M. Slattery: Electrical Review, Vol 22, Feb 25, 1893, pg 19.
3) General Electric at Fort Wayne, Indiana — A 110 year History, Clovis E. Linkous, Gateway Press, Inc., Baltimore, 1994.