In 1721 the Rev. Thomas Walter, of Roxbury, Mass., published a book comprehensively entitled 'The Grounds and Rules of Musick explained. Or an introduction to the Art of singing by Note: Fitted to the meanest capacity. By Thomas Walter, A.M. Recommended by Several Ministers.' As illustrating the Rev. Mr. Walter's qualifications to explain 'the Grounds and Rules of Musick' we would quote the following delightful and illuminating disquisition: 'There are in Nature but _seven distinct sounds_, every eighth Note being the same. Thus when a tune is sung by another upon a Key too low for the Compass of my Voice, if I will sing with the Person, it must be all the Way, _eighth Notes_ above him. I naturally sound an Eighth higher. So a Woman naturally strikes eighth notes above the grum and low sounding Voice of a Man, and it makes no more Difference than the singing of two Persons upon an Union or a Pitch. So, on the contrary, when we sing with a Voice too High and shrill for us, we strike very naturally into an Octave or Eighth below. And here let it be observed that the _Height_ of a note and the _Strength_ of singing it are too different Things. Two notes of equal Height may be sounded with different degrees of Strength so as that one shall be heard much further than the other.' This book has the honor of containing the 'first music printed with bars in America,' Mr. Tufts having omitted in his works the bars marking the measures.[11] The arrangements were taken from Playford. In 1741 Dr. Watts' 'Psalms' were printed in Boston, and an edition of Watts' 'Hymns' were printed in the same year by Dr. Franklin in Philadelphia. The next important publication was a part of Tansur's collection,[12] which was printed by William Bailey at Newburyport, Mass., in 1755, under the title of 'A Complete Melody in Three Parts.' In 1761 there was published in Philadelphia a large work called 'Urania, or a Choice Collection of Psalm-Tunes, Anthems and Hymns. From the most approv'd Authors with some entirely new: In Two, Three and Four Parts. The Whole peculiarly adapted to the use of Churches, and Private Families. To which are prefix'd the Plainest and most Necessary Rules of Psalmody. By James Lyon, A.B....' Three years later appeared in Boston 'A Collection of the best Psalm Tunes, in two, three and four parts; from the most approved authors, fitted to all measures, and approved by the best masters in Boston, New England; the greater part of them never before printed in America. Engraved by Paul Revere, printed and sold by him and Jos. Flagg.' In his preface Flagg, with admirable patriotism, pointed out that, though most of the tunes in his book came from across the Atlantic, the paper on which they were written was of American manufacture; and he hoped that the fact would recommend his book 'even to those who have no peculiar relish for the music.' We shall have more to say of Flagg in a later chapter.