I found a great review of this book from The Original Secession Magazine January 1873-1874, Vol XI, Publisher J. Maclaren, p 387-388 and there is historical context provided below as well. As you will see, the students in the church were gradually carried along to reject a cappella singing. “Most of the students sympathized with the party of liberty, which, year by year, grew stronger as these young men were licensed and ordained.” It was in this context that Glasgow wrote Heart and Voice.
“Heart and Voice: Instrumental Music in Christian Worship not Divinely Authorized” By James Glasgow, D.D., Irish General Assembly’s Professor of Oriental Languages. Belfast: C. Aitchison.
“This is a learned and laborious work. Indeed, from the amount of textual criticism it contains, we fear that superficial readers will be disposed to vote it dry. They may insinuate, too, as one critic of the book whose notice we have seen actually does, that so much digging about Hebrew and Greek roots is not productive enough to repay the labour. But the ready and sufficient answer to such shallow and flippant animadversions is, that the real teaching of Scripture on any subject can only be ascertained by a critical investigation of its meaning; and that, particularly, when the advocates of instrumental music betake themselves to the original text of Scripture, and profess to find an unanswerable argument for the organ in the meaning of this and that Hebrew and Greek word, it becomes absolutely necessary to follow them there, and to shew that their philological argument is as baseless as any and every other argument they employ.
The learned professor does all this, and more. Anxious to get to the very bottom of this important and recently much-debated question, he goes through the Bible from Genesis to Revelation, and subjects to a thorough critical examination every passage which bears, or may be supposed to bear, on the subject of instrumental music. Then, gathering up and summarizing the results, he makes it plain beyond all reasonable question that, while instrumental music was sanctioned under the Davidic dispensation, and in connection with the ritual and symbolic worship of the temple, the whole testimony of Scripture combines to shew that it is no part of moral-natural worship, that it passed away with the old ceremonial system of which (for a time) it formed a part, and that it is simple Judaism to attempt to re-introduce it into the spiritual worship of the gospel day. In the concluding chapters, he reviews and refutes the leading arguments for the use of instruments in public worship; states some subordinate objections to it; and gives a very valuable summary of opinions against it, from the testimonies of the early Fathers and of the Reformers down to those of recent writers on the subject.
On the whole, this is not a book to gallop through at a sitting. Nor is it a book which critics of the calibre who think it enough to ask you, “Does not David say, ‘Praise the Lord with a harp'”? are capable of judging. But all who are competent to follow the author through his inductive investigation of the teaching of Scripture on the subject, and who are prepared to accept of Scripture as the sole and sufficient rule of worship as well as of faith and morality, will rise from its perusal, feeling that he has proved the use of organs in the public praise of a Christian congregation to be as purely a piece of will-worship as the incense and the images of Romanism.”
The sad historical context of the book is found in A History of the Irish Presbyterians by William Thomas Latimer:
“The growth of an emotional form of worship in the Irish Presbyterian Church was now exhibited by the introduction of instrumental music to the public services of the sanctuary in some town congregations which boasted of their culture. This matter came before the Assembly in 1868, by a reference from the Synod of Armagh and Monaghan regarding the use of a harmonium in the congregation of Enniskillen.
Presbyterianism had, at one time, been strong in County Fermanagh. Under Captain M’Carmick and the Rev. Robert Kelso, a movement was originated by the leading Presbyterians which saved Enniskillen from King James, and rendered it possible to defend Londonderry. Burdy, in his life of Skelton, admits that in the middle of the next century Presbyterians were still a substantial body in County Fermanagh; but the Synod failed to establish a number of churches sufficient for their accommodation, and they were gradually absorbed by Episcopacy. Even when a revival came, it was Methodism which annexed that district. From 1837 the Rev. Alexander Cooper Maclatchy had been in charge of our Enniskillen congregation, and being somewhat Episcopal in his tendencies, he introduced a harmonium to improve the congregational psalmody. Mr. Maclatchy’s action was opposed in Presbytery, Synod and Assembly, by the Rev. James Gardner Robb, an exceedingly ready and logical debate. When this matter came before the Assembly in 1868, it was proposed to refer it to a commission, but an amendment of Dr. Cooke was carried to the effect, that ” the common law” of the Church excluded the use of instrumental music in the public worship of God, and that Presbyteries should be instructed to see that congregations conform to this ” law.”
The injunction was disobeyed, and, as an excuse for their disobedience, the “liberty” party asserted that no “law” had been passed by the Assembly, either then or previously, which prohibited an instrumental aid from being employed in the congregational psalmody. Thus the controversy was continued. Year by year resolutions were passed by the Assembly ordering disobedient congregations to abstain from using instruments in the service of the Sanctuary; but these resolutions were disregarded, and the “purity” party, although able to carry prohibitions, were unable to induce the Church to punish those who disobeyed her orders.
In these debates and in the war of pamphlets and newspaper articles, the Revs. Dr. William Dool Killers, John Macnaughtan, Henry Wallace, Dr. Robert Watts, Dr. H. B. Wilson, Dr. Thomas Y. Killen, and Dr. R. Workman, were among those who advocated the principle of permitting congregations to introduce an instrumental accompaniment in the service of praise; while the Revs. Dr. Nathaniel M. Brown, Dr. Corkey, Dr. Glasgow,* Dr. John Kinnear, George Magill, Dr. Petticrew, Dr. Robb, Dr. Robinson, and Dr. James Maxwell Rogers, advocated the principles of purity in the worship of God, and obedience to the injunctions of the Assembly. The great majority of elders were on the same side, but Mr. Thomas Sinclair lent his powerful aid to those who advocated what they termed “liberty.” Most of the students sympathized with the party of liberty, which, year by year, grew stronger as these young men were licensed and ordained.
When the purity party had a majority in the Assembly, they might have easily passed a law, with penalties annexed, prohibiting any congregation from employing an “instrument” except for the defined purpose of aiding the congregational psalmody, and only when sanctioned by a very large majority of voters. But the opportunity was neglected, and “instruments” are now introduced by “Sessions” when often there is a considerable proportion of the people against the innovation.
When Dr. Johnston was moderator, he carried a resolution pledging the Assembly, in 1873, to pass no law on the question, and binding the congregations which employed instrumental music to give up its use. But this resolution failed to settle the matter in dispute. Several of the offending ministers denied that they had entered into any agreement, and they continued to defy the authority of the Assembly.”
* Rev. James Glasgow, D.D., appointed Missionary to India in 1840, and Assembly’s Professor of Oriental languages in 1865, died in 1890. Dr. Glasgow was modest, kind-hearted, and possessed of great learning.