Question

[1]
In the 1930s, Chester Carlson, a patent attorney in New York, grew frustrated by the tedious process of copying documents. The options at the time were limited to photographic copying, which was expensive and slow, or manually retyping pages. Determined to find a more efficient method, Carlson began conducting chemical experiments in his kitchen, seeking a dry, clean way to reproduce text.

[2]
His breakthrough came in October 1938 when he successfully transferred the date "10-22-38" onto a glass slide using static electricity and a light-sensitive powder. Carlson called his invention "electrophotography." He believed the process would revolutionize office work, but major corporations were uninterested in what they saw as an unrefined, impractical prototype.

[3]
It was not until 1946 that the Haloid Company, a small photographic paper manufacturer, agreed to license Carlson's technology. Together with researchers at the Battelle Memorial Institute, they refined the process and renamed it "xerography," derived from the Greek words for "dry writing." In 1959, the company, renamed Xerox, released the first commercial automatic office copier, transforming the business world forever.

[4]
To protect his new design from being stolen by competitors, Carlson immediately applied for a patent. This legal safeguard, which he secured in 1940, ensured that he would retain control over the technology during the years he spent searching for a commercial partner.

To make the essay flow most logically, where should Paragraph 4 be placed?