The question is not simply what Sen. Howard said - his statement is informative, but not necessarily determinative (one could probably find statements made by other "framers" of the amendment that say the exact opposite - that's just how legislative debate works, and that's why Justices Scalia and Thomas often caution against over-reliance on legislative history). Rather, the question is whether, under the language of the amendment, a particular child is covered; the amendment itself does not use Sen. Howard's language, but rather uses the broader language of "subject to the jurisdiction thereof." Since, as I noted earlier, Ambassadors are the clearest example of people who are not subject to the jurisdiction, it is clear that children of Ambassadors are not covered under the 14th Amendment; with other immigrants/aliens/residents, the analysis is not nearly as clear.
OK, really going now, but I'll try to check in on the thread throughout the day.