The Magnus cocktail

Guess what, I've got my own cocktail! The recipe is from the 1910 edition of Jack's Manual - it's possible that it can be found elsewhere too, but I'm too lazy at the moment to find out. Anyway, here's the recipe - enjoy!

Magnus (1910)
1 dash Angostura bitters
Juice of ½ orange
Peel of an orange in one string
Place in glass
50% (Gordon's) dry gin
1 bottle (imported) ginger ale
Stir and serve.

Well, the juice of ½ orange is 50-60 ml, and according to Mr. Jacob A. Grohusko, the author of the book, 50% is ½ jigger (30 ml). I think I need to play around a little with the proportions... ;-)

Edit: found an updated recipe in the 1933 revised edition:

Magnus (1933)
2 dashes angostura bitters
Juice of half an orange
Peel of an orange in one string
100% gin
1 bottle ginger ale
Stir and serve.