The disputed fourth Core Discipline, Thaumaturgy, is the study of phenomena outside the traditional purview of the core three. It is a difficult science to break into, as "experts" are rare, and their willingness to share rarer still. Additionally, even entertaining the idea of its existence would be grounds for expulsion from the Institute. Here lies the study of "Magic", "Souls", "Sparks," and other such concepts.
Power is an Applied discipline of Physics, and responsible for generating and manipulating energy in its various forms. Steam, Electricity, and even a new fangled concept called "Radioactivity" can be studied.
Your brother Michael is a few years you senior, and took after your mother. You've not spoken to him in years, except in the most vague of pleasantries. He never held to the idea that a Lady could have a Gentleman's hobbies, but kept that mostly contained whilst you both lived under your father's roof. That you even received a stipend from him was surprising, but perhaps your father had something to do with it.
You do have two other siblings though, both younger than you. Whilst you weren't overly close with either of them (personal skills not being a talent of yours), it was certainly warmer than with Michael. Your younger sister Beatrix is a classic young lady, and seems happily married to her husband Sir Richard Latton, living somewhere on the other side of the City. Your youngest brother Hugo actually seemed to enjoy your company as he was always following you around. Last you heard he was gallivanting across the continent, pursuing a life in the Arts.