Company Names, addresses, dates:
  Dr J.S. Irwin (Physician), Woodstock VA, (c.1851)¹
  Dr J.S. Irwin & Son, Opp Court House, Woodstock VA, (1878-1882) ^2,3
  Dr J.S. Irwin & Son, N.E. Corner of Court & Main, Woodstock VA, (1882-18??) ^4,5
  Irwin Bros., Woodstock VA, (c.1883) ⁶
  Irwin Bro & Co, Woodstock VA, (c.1883-1888) ^7,8
  F.R. Irwin, Woodstock VA, (1888-1894) ^8,9
  F.R. Irwin & Bro, Woodstock VA, (1890-1891) ¹⁹
  F.R. Irwin & Co, Woodstock VA, (1891-1891) ¹⁹
  Irwin's Drug Store, Woodstock VA, (c.1894-c.1897) ⁹
  Lin Irwin, Woodstock VA, Opp Court House, (1897-1906) ¹⁰

Notes:
Dr. Joseph Swift Irwin (1811-1895)¹¹ was a physician in Woodstock. His son Dr. Henry H. Irwin also became a physician, and his sons Joseph S.L. Irwin, Franklin R. Irwin, and Linden R. Irwin all became druggists.
Dr. Irwin opened a drug store under the name J.S. Irwin & Son on April 1st, 1878. The son was Joseph S.L. Irwin, and the store was located on Main street, opposite the Court House.^2,3

Joseph S.L. Irwin (b.1856)¹² is listed as a druggist with the Gilbert Bros & Co drugstore in Baltimore MD in ads from 1879-1880^13,14. In 1885, he opened a drug store in nearby Mt.Jackson VA.¹⁵

Dr. Henry H. Irwin (b.1860)¹² was a physician - I have found no evidence that he was a druggist. In 1887, he moved his practice from Mt. Jackson to Woodstock. ¹⁶ Henry was listed as the son in an 1887 ad for "J.S. Irwin & Son". Even though the firm name was the same, the 1887 ad¹⁷ listed "J.S. Irwin & Son" as physicians/surgeons, whereas the 1878 ad listed "J.S. Irwin & Son" as a drug store.²

Franklin R. Irwin (1858-1895)^12,21 was likely one of the brothers in the firm "Irwin, Bro. & Co" during the 1880s. In 1887, there were mentions of 3 firms: "Irwin, Bro. & Co", "Irwin & Son", and "J.S. Irwin" in Woodstock¹⁸.
In 1888, Franklin took over the firm "Irwin, Bro. & Co".⁸ Ads refer to the firm as "F.R. Irwin" from 1888-1894, but some ads in 1890-91 refer to "F.R. Irwin & Bro", and some ads in 1891 refer to "F.R. Irwin & Co.".¹⁹ It's not clear whether there were name changes going on, or if there were multiple drug stores. The "& Bro" and the "& Co" were probably referring to brother Linden, but none of the ads seem to mention who the brother/partner was.¹⁹

Linden R. "Lin" Irwin (1864-1922)²⁰ was a successful druggist in Mt Jackson in 1887. In 1895, after his brother Franklin died, he took over Franklin's drug store.²¹ Ads refer to it as simply "Irwin's Drug Store" for a few years after that, but there are also ads for "L.R. Irwin, Druggist" starting in 1896, so the drug store seemed to gradually take on Lin's name. Lin moved to Richmond VA, and was the manager of Scott's Pharmacy when he passed away on July 5, 1922²²


F.R. Irwin Bottles:

This is a 3.4" clear bottle embossed: vertical in slugplate: F R IRWIN / DRUGGIST / WOODSTOCK, VA. base: C L G CO

This is a 4.3" clear bottle embossed: vertical in slugplate: Lin Irwin / DRUGGIST / WOODSTOCK, VA. base: PAT JUN 17 88 / S.B.