has he designed anything else apart from the coin?
Yes, Indian Head cent, Shield nickel, and Flying Eagle cent.
James B. Longacre
 Longacre is best known for designing the Indian Head cent, which entered commerce in 1859, and for the designs of the Shield nickel, Flying Eagle cent and other coins of the mid-19th century.

what is the gold dollar? A gold coin when was it first struck? 1849 and who issued this coin? United States Bureau of the Mint what is this coin made of? Gold who is the design of the coin attributed to? James B. Longacre where is he from? Delaware County, Pennsylvania did he participate in any war? No
wiki:13972426
James B. Longacre [SEP] Introduction
Peale and Patterson nearly had Longacre fired, but the chief engraver was able to convince Treasury Secretary William M. Meredith that he should be retained. Both Patterson and Peale left the Mint in the early 1850s, ending the conflict.