7. There is a more obvious string instrument in the sky than that in Gemini, viz. in the Lyra constellation:

Hevelius has drawn his Lyra constellation as a great flying bird (manu rere).

Vega (α Lyrae) ought to be in the G text, it is a very bright star:

  ω Gemini 5.20 24° 13′ N 06h 59m 106.4 514.4

Vega

 α Lyrae 0.03 38° 44′ N 18h 35m 282.8 690.8

To find the Vega glyph we should proceed as when we found Ga2-11, viz. by reducing 514.4 by 472. Thus it should be in position 690.8 - 472 = 218.8:

Ga2-9 Ga2-10 Ga2-11 (42)
  Alhena (104.8) Adara (105.8), ω Gemini
Ga8-13 Ga8-14 (218) Ga8-15 (*283) Ga8-16
  Vega (282.8)  

8-15 suggests 8 right ascension hours (because each such hour corresponds to 360 / 24 = 15 days). 8 * 15 = 120 = half 240 = ⅓ * 360.

But we ought rather to count 81 * 5 = 405:

Gb6-17 Gb6-18 Gb6-19 Gb6-20
Gb6-21 (*468) Gb6-22 (405) Gb6-23 Gb6-24

It does not seem to make much sense. However, if we count the distance from ω Gemini to Vega it does make sense, because there are 177 (= 6 * 29½) days from the one to the other:

176 253 41
Ga8-15 (219) Ga2-11 (42)
Vega ω Gemini

From α (Vega) to ω (Gemini) there are 295 days, 10 lunar months. 691 + 295 - 472 = 514.