From 1814, missionaries tried to define the sounds of the language. Thomas Kendall published a book in 1815 entitled "A korao no New Zealand", which in modern orthography and usage would be "He Kōrero nō Aotearoa". Beginning in 1817, Professor Samuel Lee of Cambridge University worked with the Ngāpuhi chief Tītore and his junior relative Tui (also known as Tuhi or Tupaea), and then with chief Hongi Hika and his junior relative Waikato; they established a definitive orthography based on Northern usage, published as the "First Grammar and Vocabulary of the New Zealand Language" (1820). The missionaries of the Church Missionary Society (CMS) did not have a high regard for this book. By 1830 the CMS missionaries had revised the orthography for writing the Māori language; for example, ‘Kiddeekiddee’ became, what is the modern spelling, ‘Kerikeri’. This orthography continues in use, with only two major changes: the addition of "wh" to distinguish the voiceless bilabial fricative phoneme from the labio-velar phoneme ; and the consistent marking of long vowels.