In 1886 – the year this letter was written – Grover Cleveland was the president of the United States, and the transcontinental railroad had just been completed. Steam engines were the main form of power generation, but Thomas Edison was working with a “system of electric lighting” for which he used Vacuum Oil to lubricate his turbines. Energy use has certainly changed over time, as have the companies referenced in this letter – Edison created what is now GE, and Vacuum Oil became ExxonMobil. GE is still a leader in making electric generating turbines, and we’re still keeping turbines running with lubricants. Time flies when you’re having fun!