I'll try to help you, but unfortunately I'm neither very good at reading old German handwriting nor at translating from German into English. Hopefully, someone else will fill in the gaps and correct any mistakes I might have made. Hope it helps
Second letter:Transcription:Chemnitz, d. 15.4.1931.
Liebe Nichte Ruby!
Wie [?] Pearl, so sende ich auch Dir eine Gedenkkarte an den früheren
deutschen Postminister Stephan. Je [?] eine Oberschlesien Gedenkkarte über die
am 22. März 1921 erfolgte Volksabstimmung, darüber ob Oberschlesien
beim deutschen Reiche verbleiben solle, ließ ich Euch besonders zugehen.
Diese Karten haben nur eine einmalige Ausgabe und werden selten.
Wir senden Euch gleichzeitig eine Klavier-Note und hoffen, daß Ihr auch
die
Note [?] mit den 2 deutschen Märschen bekommen habt. Sollten
diese
Noten [?] Euch gefallen, so werden wir öfter ein Blatt mitschicken,
die Ihr dann zu einem Buch vereinigen könnt.
Wir haben aus Eurem letzten Brief erfahren, daß Ihr unsere Bilder
und die erzgebirgischen Lieder erhalten habt und daß Ihr auch schon
die Melodien erlernt habt.
Nächsten Sonntag fahren wir nach Stollberg und werden Euren l. Brief
dort d Eltern zum Lesen geben.
Euch allen freundliche Grüße
Emilfriedaelfriedeuhorst
English translation:Chemnitz, 15/4/1931
My dear niece Ruby,
Like Pearl, I am sending you, too, a card commemorating the former German Postal Minister Stephan. Separately, I have sent each of [?] you an Upper Silesia memorial card about the plebiscite that took place on March 22, 1921 and dealt with the question as to whether Upper Silesia should remain a part of the German Empire. Only one edition of these cards was ever printed and they are becoming rare.
At the same time, we are sending you piano sheet music and we hope that you have also received the
sheet music [?] with the two German marches. If you like this
music [?], we will send you a sheet with our letters more often from now on, which you can collect in a book.
We learned from your last letter that you received our pictures and the songs from the Ore Mountains and that you have already learned the melodies. Next Sunday we are going to Stollberg and we will show the parents your d[ear] letter.
Many greetings to you all.
Emil, Frieda, Elfriede and Horst
First Letter
Transcription:24. März 1931
Liebe Nichte Ruby.
Herzlichste Glückwünsche zum Schulerfolg und zum
weiteren Streben
von Deinem Onkel Emil, Tante Frieda
Elfriede und Horst
Abs. E. Lohse, Chemnitz, Fabriciusstr. 6.
Gebt sofort Bescheid, ob Karte[n] an Dich u. Pearl eingegangen sind.
An Vater [?] u.
Mutter [?] sandte ich Ende März ja eine solche Karte.
English Translation:March 24, 1931
My dear niece Ruby,
Congratulations to your success in school and your further studies/efforts.
Your Uncle Emil, Aunt Frieda, Elfriede and Horst
From: E. Lohse, Chemnitz, Fabriciusstraße 6. Tell us at once if you and Pearl have received the card(s). As you know, I sent such a card to
father [?] and
mother [?] at the end of March.
Related Links:
"Heinrich von Stephan (January 7, 1831 – April 8, 1897) was a general post director for the German Empire who reorganized the German postal service. He was integral in the founding of the Universal Postal Union in 1874, and in 1877 introduced the telephone to Germany."
http://en.wikipedia.org/wiki/Heinrich_von_Stephan"The Upper Silesia plebiscite was a border referendum mandated by the Versailles Treaty and carried out in March 1921 to determine a section of the border between Weimar Germany and Poland."
http://en.wikipedia.org/wiki/Upper_Silesia_plebisciteFabriciusstraße 6 in Chemnitz on Google Maps:
https://maps.google.de/maps?hl=de&tab=wl