1992年清明時節，美國人考古學家K. J. 施羅德(K. J. Schroeder)邀請我和他一起到鳳凰城先民和軍人紀念墓園(Pioneer and Military Memorial Park)考察華人墓葬和清明節掃墓習俗。那次我們確認了墓園裏唯一的一塊鄧湘遠中文墓碑。
施羅德問了我好多有關華人掃墓的問題，我詳細地向他講述了清明節華人掃墓的風俗習慣。1994年施羅德主編Pioneer and Memorial Park Archaeological Project in Phoenix Arizona 1990-1992，在該書第二卷的第三章和第十七章裏，記錄下我的講述。下面是摘錄。
1992年4月5日，唐孝先(William Tang)（左）和K. J. Schroeder （右）合影於鄧湘遠中文墓碑旁。
Another annual event is the Pure Brightness Ceremony, a Chinese traditional occasion honoring the dead. This ceremony usually occurs on April 5. For a couple of years it was puzzling to the PCA(Pioneer Cemetery Association) members when they arrived to work at the cemetery, as to who was burning incense and wax candles in front of the gates at P&MMP(Pioneer and Military Memorial Park). The mystery was solved when William Tang, a visiting scholar from China, was asked to interpret the Chinese characters on a tombstone at City Cemetery. From him, it was learned that the Pure Brightness Ceremony is performed by the descendants of the dead, and serves to prevent evil spirits from entering the cemetery site. The PCA has since then made every effort to have the cemetery gates open to the Chinese for the Pure Brightness Ceremony.
The members of the Pioneers’ Cemetery Association (PCA) had, for a number of years, been puzzled by the occasional presence of ashes, melted candles, and partially burned, thin sticks found at the gates of the cemeteries at the Pioneer & Military Memorial Park (P&MMP). These items were found at temporarily isolated intervals, i. e., once every spring, and would be present when PCA members of the arrived to work at the cemeteries. Another puzzle was the interpretation of the Chinese characters on a tombstone at the P&MMP. This tombstone is located within what has come to be known as the Chinese Circle and is part of City Cemetery.
In an effort to have the inscription on the tombstone interpreted, the senior author invited William Tang, a visiting Chinese scholar at Arizona State University, to the cemeteries. The results of Tang’s interpretation and additional studies into the history of the individual buried there will be presented under separate title. However, as a spin off of this investigation, the mystery of the first puzzle was solved.
According to Tang, the materials found at the entries to the cemeteries resulted from an ancient Chinese ceremony in honor of the dead known as the Pure Brightness Festival, or Qing Ming. The remains found were the burned remnants of paper money, hand made wax candles, and sticks of incense.