Caroline “Carrie” Florence Siedle (née Slader) was born in England on April 15th, 1853, daughter of Samuel and Elizabeth Slader. At the time of her death on February 26th, 1907, she was a renowned and well respected designer of costumes for the American stage. In a widely quoted obituary, the director Julian Mitchell was reported as saying:“Death in removing Mrs. Siedle has deprived me of the helper who enabled me to make my reputation,” … “Without her assistance I should never have been able to carry out the musical comedy color schemes which have made beautiful stage pictures. Her taste was always good, and her ability to design amounted to genius.”
Although her obituaries would list her age as around 40, she was 53 at the time of her death. A bout of pneumonia was the cause, unexpectedly taking a valuable asset from the New York theater world. She is buried in Woodlawn Cemetery, in the Bronx.
There isn’t much information about Caroline's early years in England. Her maiden name was Slader, and her birth registry lists her name as Florence Caroline; at some point she reversed her first and middle names. According to interviews her father was a wood engraver; possibly related to Samuel Machin Slader, an English wood engraver active in the 1820s – 1840s. One of her brothers was an artist, while another brother was an engineer, and Caroline studied art at the South Kensington School in London. She did some illustration and fashion design work; on the right is a published illustration from before her marriage (date and place of publication unknown). But it was after her marriage to Edward Siedle that her career blossomed.

Information is vague; apparently Edward emigrated to the USA in 1878, and married Caroline in 1883, but I've found no definite information on when or how Caroline came to America. An 1881 British census lists her parents and a daughter named Elizabeth, who appears to be an older sister. Caroline and her brothers are not included, indicating that they no longer lived at home. I don't know whether Caroline and Edward were acquainted in England, or met after both were in the USA. Perhaps Edward established himself in his new country, then sent for her; a five year engagement was not uncommon during the Victorian period. On the wedding certificate her name is amended to Florence Caroline, just like her birth registry. Edward’s last name is spelled Seidle rather than Siedle, a mistake that would continue to occur through the rest of her life.

Edward had worked as a props man in London, and traveled to the USA with the theatrical manager Lester Wallack. Around 1891, after a few years with other companies, he began working at the Metropolitan Opera in New York City. He eventually became a well known and legendary property master and technical director for the company. Caroline provided illustration work to magazines such as Harper’s and St. Nicholas; on the right is an undated example of her work from one such publication. She also did tapestry painting for theatrical scenery. She was one of the few women to work in scene painting, and assisted her husband on various productions; she provided painted tapestries based on designs by Raphael for an 1890 staging of Judah that played Broadway and toured the country. The scenic work helped her to learn the properties of various colors on the stage, which became a cornerstone of her costume work.According to published accounts, her career in costuming started when she suggested a solution to her husband for a problem with harmonizing colors in a production that was causing him difficulty. The success of her idea led to his suggestion that she might consider costuming as a career, and the rest is history! Her first production was The Knickerbockers, adapted by Harry B. Smith and Reginald de Koven from Washington Irving’s History of New York, and produced in 1893 by The Bostonians.
An article/interview with Siedle from May 1st, 1896, in the New York Journal credits her with new ideas in theatrical staging:
The carrying out of a series of distinct color schemes in the staging of a comic opera is a comparatively new departure. The success, however, of the venture in the recent production of “El Capitan” at the Broadway Theatre has proved that the public eye is capable of appreciating an ever-changing symphony of delicately undulated color quite as much as the time-honored custom of adorning groups of women in the seven primary hues.
Mrs. Edward Siedle, who designed the costumes for “El Capitan”, is really the originator of the idea of staging an opera so that each act is a separate, beautiful tone picture, and not a disconnected rainbow.
It was not uncommon for both Caroline and Edward to contribute to a production, in the form of costumes and props. Both had offices at the Metropolitan Opera Company, and Caroline also had a studio in their home in Yonkers, shown on the left ca. 1902.
The Siedles had a son, also named Edward, who was born in 1888. He served in the first World War and married in 1920. The couple lived in Rye, New York and had two daughters and a son. Edward Jr. died in 1965. 
Edward Siedle Sr. did remarry after Caroline’s death, as there was another Mrs. Siedle by 1914. Edward died in 1925.
Caroline Siedle’s designs have scattered in the decades since her death. There are several institutions with large holdings - the Performing Arts division of the New York Public Library, The Shubert Archive, The Museum of the City of New York; other acquisitions turn up, like the collection at the McNay Museum in Texas, or in the Library of Congress, and private collectors eagerly seek examples of her work. As an 1895 article about Caroline pointed out:Anyone
who is hunting for a new collection fad might take a hint here. When
the designs are completed and sent to the purchaser, every one of them
is a little watercolor gem of a figure, and so full of action that often
they are preferred to portraits as foundations for the posters of a
company. What becomes of all these sketches isn't stated, but if they
could be secured they would make an immensely interesting collection.
Siedle family photos and documents are used courtesy of the Siedle descendents.