[ Gentleman's Magazine ]
The Gentleman's Magazine was an important and influential monthly magazine in the 18th and 19th Centuries; it began in 1731, ceased regular publication in 1907, and shut down completely in 1922.
The issue of April, 1789, carried the following obituary notice:
In a miserable garret, in an advanced age, Captain Barber, one of his Majesty's regiments of foot. He had been for many years on half-pay, and lived in a very close and retired manner. He was remarkable for being always followed by a Newfoundland dog, to which he was particularly attached. He has left a legacy of 4000£ either to the Foundling or Magdalen Hospital. He had a sister, to whome he has bequeqathed only 10£ a year.
As an aside: those money amounts don't make sense to me. 4000£ in 1789 would be almost $700,000 US (in 2021), and it certainly doesn't sound as though the good captain could scrape together those kinds of savings on a half-pay salary, even if living in a "miserable garret" meant he saved a lot on rent. (Although it is true he wouldn't have been the only person to have lived in a very understated manner while accumulating surprising wealth.)
In the original text, the standard pound sign (£) is not used; rather, the money amounts are followed by what appears to be an "l" (that's the lower-case letter, not the number one). It was not uncommon for the pound sign to be replaced with an "l" in certain publications at the time, as the pound sign itself had originally evolved from the letter "l" (from the Latin libra, which was an ancient unit of weight used by the Romans). So I'm assuming that the pound sterling is what is meant. If shillings were intended — the shilling was sometimes denominated with an "/-" instead of the customary "s," then the captain left about $34,500 US to a hospital, and $86 US to his sister. Of whom he apparently was not particularly fond no matter which way you figure it....