Thanks to Tom Hughes for passing along this collection of quotes on the manner of baptism from important figures in church history:
Cyril of Jerusalem (mid-fourth century)
"You are about to descend into the baptistry in order to be plunged in water. . . . For he who is plunged in water is surrounded on all sides by water." (Catechism, 3, 17)
"After you professed your belief, three times did we submerge . . . your heads in the sacred fountain." ( Homilies, 4. Quoted in Hinton, A History of Baptism)
The Council of Celchyth (Canterbury, England, A.D. 816)
"Let ministers take notice that when they administer the holy baptism, that they do not pour the holy water upon the heads of the infants, but that they be always immersed in the font; as the Son of God has in His own person given an example to every believer, when He was thrice immersed into the waters of the Jordan. In this manner it ought to be observed." ( Canon 6)
"Baptism may be given not only by immersion, but also by affusion of water, or sprinkling with it. But it is the safer way to baptize by immersion, because that is the most common custom." ( Summa Theologiae, Part 3, Quaest. 66, Art.7)
"The washing [of baptism] preacheth unto us that we are cleansed with Christ's bloodshedding, which was an offering and a satisfaction for the sin of all that repent and believe, consenting and submitting themselves unto the will of God. The plunging into the water signifieth that we die, and are buried with Christ, as concerning the old life of sin which is Adam. And the pulling out again, signifieth that we rise again with Christ in a new life full of the Holy Ghost, which shall teach us and guide us and work the will of God in us, as thou seest Rom.VI." ( Obedience of a Christian Man, 1571 edition, p. 143.)
"On this account (as a symbol of death and resurrection), I could wish that such as are to be baptized should be completely immersed into the water, according to the meaning of the word, and to the significance of the ordinance, not because I think it necessary, but because it would be beautiful to have a full and perfect sign of so perfect a thing; as also, without doubt, it was instituted by Christ." (Luther's Works, 1551 edition, Vol. 2, p.76)
"If you consider what baptism signifies, you will see that the same thing [immersion] is required. For this signifies, that the old man, and our sinful nature, which consists of flesh and blood, is all submerged by divine grace, as we shall more fully show. The mode of baptizing ought, therefore, to correspond to the signification of baptism, so as to set forth a sure and full sign of it." (De Sacram. Bapt. Quoted by Conant, The Meaning & Use of Baptizein)
"First, the name baptism is Greek; in Latin it can be rendered immersion, when we immerse any thing into water, that it may be all covered with water. And although that custom has now grown out of use with most persons (nor do they wholly submerge children, but only pour on a little water), yet they ought to be entirely immersed, and immediately drawn out. For this the etymology of the name seems to demand." (On the Sacrament of Baptism)
Then also without doubt, in German tongues, the little word tauf [baptism] comes from the word tief [deep], because what one baptizes he sinks deep into the water." (Luther's Works, Vol. 21, p. 229)
"'Into his death.' When ye were immersed into the water of baptism, ye were ingrafted into the death of Christ; that it, the immersion of your body into water was a sign, that ye ought to be ingrafted into Christ and his death, that as Christ died and was buried, ye also may be dead to the flesh and the old man, that is, to yourselves." ( Annotations on Romans 6:3).
". . . it is evident that the term baptize means to immerse, and that this was the form used by the primitive church." ( Institutes of the Christian Religion, Book IV, Chapter XV, Paragraph 19).
"I believe (myself) it is a duty to observe, so far as I can . . . to baptize by immersion." (Moore, Life of Wesley, Vol. 1, p. 425)
"Mary Welsh, aged eleven days, was baptized according to the custom of the first church and the rule of the Church of England, by immersion." ( The Journal of the Rev. John Wesley, Vol. 1, pp.24). On May 5 he refused to baptize a child whose parents would not admit immersion. (p.29)
Philip Schaff (famous Presbyterian Church Historian)
"Immersion, and not sprinkling, was unquestionably the original, normal form of baptism. Immersion shows the very meaning of the Greek word baptize." ( Schaff's History of the Apostolic Church, p.568)
John Wall (Episcopalian author)
"Immersion was in all probability the way in which our blessed Savior was baptized, and certainly the most used way of baptism." ( History of Infant Baptism, Vol. 1, p.571)
Dean Stanley (Anglican)
"For the first thirteen centuries the almost universal practice of baptism was that of immersion. They were plunged, or immersed in water." ( Christian Institute, p.17)
George Campbell (President of Marischal College, Aberdeen)
"The word baptizein, both in sacred authors and in classical, signifies 'to dip,' 'to plunge,' 'to immerse,' and was rendered by Tertullian, the oldest of the Latin Fathers, tingere, the term used for dyeing cloth, which was by immersion." ( Translation of the Gospels, Matthew 3:11)
J. A. Turretin (Professor of Theology at Geneva)
"And indeed baptism was performed, in that age and in those countries, by immersion of the whole body into water." ( On Romans 6:3-4. Quoted by Conant, The Meaning and Use of Baptizein)
"But that, in accordance with the nature of the word baptizesthai, baptism was then performed not by sprinkling upon but by submerging, is proved especially by Romans 6:4." ( Commentary on the Gospel of Matthew, Vol. 1, p.120)
"In the primitive Church, and down to the fourteenth century, the ordinary mode of baptism was by immersion of the whole body in water. The original term baptize conveys the meaning of immersion, and no other. On this point we have most valuable testimony from the Fathers of the Church, and other ecclesiastical writers. They invariably designate baptism as the act of dipping, bathing, or washing."
( The Archaeology of Baptism, p. 16).