The only information I can presently locate about Machen is that it was once a stop on the Central of Georgia Railway line that ran through here, along the Eatonton-Covington route. It’s essentially part of Shady Dale today, but a railroad marker near this house (and a few good maps) still proclaims it to be Machen. I hope to learn more. This modified American Foursquare house was built in 1915.
Vanishing Georgia: Photographs by Brian Brown 
Machen was a part of Sherman’s March to the Sea. The two flanks split just outside of Covington (I think). See the book about Dolly Lunt Burge/Burge Plantation, Newton County, GA, a historical documentary.
There is also a Historical Marker.