The Thomson-Houston Electric Company was founded in 1883 by a group of shoe manufacturers based in Lynn, Massachusetts. Those investors, led by Charles A. Coffin, bought out Elihu Thomson and Edwin Houston's American Electric Company from their New Britain, Connecticut investors. Like the Gaulard and Gibbs transformer, the Thomson-Houston had a number of patent conflicts. But unlike Gaulard and Gibbs, they had the backing to pull a Google and just buy up the damn patents. In 1889 they bought out Charles Brush and ended their biggest problem. More here.
Their 2nd biggest problem was Westinghouse. In 1886 Westinghouse took it's improved Stanley transformer and installed it's first arc light system in Buffalo at an existing Brush Co. station. That same year Westinghouse won out on a patent for AC distribution over Thomson-Houston. To his credit, rather than fight Westinghouse endlessly patent-by -patent, Thomson convinced them to share. By 1887 Thomson-Houston was manufacturing Westinghouse arc systems, and Westinghouse had a license to sell Thomson-Houston arc lighting gear. The deal lasted 2 years, ending when the Westinghouse patent was declared invalid. It didnt' matter, Thomson had been hard at work trying to circumvent the patent anyway. The MBAs call it coopitition now.
Thomson was on a 2-year tear, patenting more transformer models; different shapes, different laminations, different cores and eventually a core that sat insulated in an oil bath. When the Westinghouse patent died, Thomson-Houston patents were unavoidable. Westinghouse will owned the Albert Schmid improvements to the Stanley design, but they were otherwise in a sea of Thomso's patents. In 1890, Fleming wrote that there were 100,000 lamps using the AC dynamo in the Thomson-Houston system. He went on to describe their transformer.
"The field magnets are of cast iron, and are made in two parts, the lower one bearing the pedestals for the armature bearings. Each casting carries projecting inward from it one-half the total number of radial pole pieces. The number of polar projections varies from eight in some of the smaller sizes to twenty-two in the largest. The armature is a laminated iron cylinder, and has applied to its surface a set of flat coils which form one layer of double-insulated copper wire of square cross section. This armature winding consists of a number of flat oval coils, equal in number to the number of polar projections, wound in a lathe on special formers, and curved so as to fit the cylindrical surface of the iron core. There is a space of three-quarters of an inch or more In the centre of each coil which, in some machines, is filled with an insulating slip or core, and in others with a second separate coil used for exciting the field of the dynamo. The armature coils are securely bound to the armature core by German silver wire, and are covered with insulating strips of mica. These coils are either connected all in series and in series with the external circuit..."
You can see from that description that this transformer also draws heavily on those that came before it.Nonetheless the Thomson-Houston Co. patents were legit because they were narrow and specific. In 1892, Thomson-Houston merged with the Edison General Electric Company and history rolled on. In 1909, Thomson became the first recipient of the Edison Medal, bestowed by the American Institute of Electrical Engineers AIEE, what we now call the IEEE. He was president of the organization from 1889-90, and acting president of MIT from 1920-1923. He died in 1937. Edwin J. Houston was president of the IEEE twice actually, he took a different path, forming a consulting firm in 1894 with Arthur Kennelly.
There is a lot more to be said about Thomson-Houston and GE. I recommend the book Innovation as a Social Process: Elihu Thomson And The Rise of General Electric by W. Bernard Carlson. There were other important transformers that followed but most of them were a part of the natural progression to make components smaller. Here's a short list of models I didnt get into for those of you who are obsessive enough to read more.
Charles Brush Transformer - 1881
Lowrie-Hall Transformer - 1886
Mikhail Dolivo-Dobrovolsky Three-Phase transformer - 1888
Swinburne-Hedgehog Transformer- 1890
Oerlikon Transformer- 1891
Siemens Cable Transformer - 1891
Frankfort-Laffen Transformer 1892
Schuckert Transformer 1894
Elkhart Transformer - 1894