Linguaphone Records Info

[mrvic2]

Hello Everyone.
A few days ago I went to a local record store & among some other finds, I found these two Linguaphone discs, parts 1-4 of a French lesson. I don't know much about this company, so I have a few questions that I need answered, if you could, please answer them or direct me to a place where they could be answered.
1. Are these records Electric or Acoustic?
2. What year/range of years do these come from?
3. How many records are in the full French Lesson set
4. Any other information about this company &/or these records that you feel is important.

Thank you all for your help in advance, I have closer up pictures of the label if they are needed/if TMF makes these photos too blurry.