Emily. I do not know how long you have been researching, but the previous responders are trying to be polite. It may be Gass as you know it, and know it now, and maybe even then, and you may be lucky enough to find it under that spelling. However, a large percentage of people of the time could barely read and/or write, much less spell well. Like they said - clerks and scribes of any kind wrote things down as they sounded (ie, spelled like they sounded, but not as the person spelled it), or through writing/transcribing errors (it was spelled wrong along the way.It is particularly common with names that have known variations in their spelling. In my case Ingram/Ingraham; Kyle, Kile, Coil; Cleveland/Cleaveland and so on. Most people have some. They usually prove it by reconciling it with other records. People researching immigrants know that many from other countries "Americanized" their names so as not to appear different, or simply liked the way it sounded another way. It's very common, and the documented cases are legion. I have an ancestor whose (recorded) will has his name spelled three different ways in the one document. (he signed with "his mark", which was and X, like many did so long ago, when they were illiterate). So obviously the scribe (which he probably felt fortunate to have someone who could read and write), could not spell very well. This is not an uncommon situation, so people who do a lot of researching almost always try several different spellings. If you don't, you can miss some good stuff, that turns out to be the real deal... Good luck.