From the history of instrument

Unfortunately very little is known about the history of the church's oldest instruments. We only know that by 1415 the organ had been already installed. In Memories of Prague's Riot A.D. 1524, (FRB VI, 303) is written:

„In 1415 there was a parson in Prague called Zikmund who kept one parsonage at St. Stephan's in the New Town and an another at St. Martin's in the Old Town. When he had seen that people had been venerating the paintings, at first he exposed the monstrance with the Corpus Christi… and so was persuading the people that everything they were doing was made to the honour of this monstrance and they were singing and playing the organ… and so filled the people's eyes and ears that blind and deaf it became and so the God's words and God himself forgotten were. - Then they made a parade every Thursday around the Church and a glorious mass with cantors and organ, new prayers, strange ceremonies and a church pride born with this monstrance"

In the period of Baroque a new instrument was built. It had a positive in the choir railings and its case was divided into two parts that let the light in from the main window. That organ had 22 stops and in the middle of 19th century it was still recognized among the best instruments of all Prague churches. But at those times it was already in a very poor condition, even after several repairs. So in 1876 - 1879, in connection with the regotisation of the church, the rectory began to think about a new organ. However that idea was realised only 10 years later.
Into the budget of 1886 a sum of 6000 golden (former Austrian coin) was added for the organ construction and the new disposition was worked out by Otomar Smolík, a local choir regent. Smolík supported the new construction for the following reasons:

1. „According to the inner form and the outer style, the present organ is about 200 years old;
2. so the wind chests are damaged by woodworms and are under decay;
3. bellows and the air chambers are worn out and also destroyed by worms;
4. Pipes and trackers were destroyed during the church restoration in 1879, but by that time the greatest part of the organ had been already in a poor condition; during the reconstruction, the wooden pipes were destroyed with stones, the tin pipes were curved and most of them were stolen. An organ builder, Eisenhut by name, was called to examine the organ, and he said that the following stops were destroyed:
   
   IN MANUAL: Bourdon 16', Salicional 8', Gemshorn 8', Copula 4' and Mixture
   IN PEDAL: Quintbas, Violon a Subbas 16',
   
   and that the playing mechanism was mainly destroyed and if one started playing some key could stick and by bad luck cause an odd noise disturb the dignity of the mass."

Several organ builders presented their offers: Josef Mauracher, organ builder at the St.Florian near Linz, Karel Schiffner, organ builder at Prague, Em. Š. Petr, organ builder at Prague and Rieger Brothers, establishment in Krnov.
The construction was committed to Rieger Brothers and cost 6400fl. r. m. By the end of the year 1887 the works were already so complete that the disassembly of the old instrument was necessary. The wooden decorations were stored in the St.Longin's chapel, other wood and boards were transferred to Podskalí where the municipal storeroom was. But the built shouldn't interrupt the organ playing so the positives in St.Nicolas at Malá Strana and in Týn church were examinated, the best one tuned and stored at the St.Stephan's church. It was probably the St.Nicolas's positive, which had been chosen because it was found more then 40 years later in the storeroom behind the church. The cost of the old organ was estimated to 150 golden. Finally, the parsonage accepted the Eisenhut's offer:

1. Pipescreen pipes 1kg to 1 golden
2. Inner pipes with lead alloyed 1kg to 80 "mite"
3. Positive with wooden pipes and accessories 20 golden

According to this table, Eisenhut paid: for metal pipes 90 golden, for the positive with accessories 20 golden and for the old wormy wood 9 golden. 119 golden in total. From that amount 57 golden 2 mite were paid for the floor repairing, the railings and choir's masonry damaged when replacing the old organ. The new instrument was faultless, passed on the 20 December 1887. The commission only requested that the name of the firm and stops names were made in Czech rather then German (stops in Czech or Latin).
The disposition remained unchanged. The manuals are scaled by force and disposed by orchestral voices in the equal tone:

I.Manual (Great Organ):

1.Bourdon................16'	7.Octave..................4'
2.Principal..................8'	8.Dolce....................4'
3.Gedäckt...................8'	9.Quinta.............2 2/3'
4.Spitzflauta................8'	10.Octave..................2'
5.Gamba.....................8'	11.Mixture.............-,5x
6.Aeoline....................8'	12.Basson - Oboe......8'

II.Manual (Positive):

1.Geigenprincipal......8'	5.Flute......................4'
2.Lieblichgedäckt......8'	6.Gemshorn..............4'
3.Salicionale...............8'	7.Kornet................-,4x
4.Vox coelestis..........8'

Pedal:

1.Principalbas..........16'	4.Octavebas................8'
2.Subbas..................16'	5.Cello.........................8'
3.Violon...................16'	6.Posaun....................16'

Couplers: II/I, I/P
Choirs: Mezzoforte I, Forte I, Forte II, Forte Pedal, Pleno
Crescendo, Combination

In 1917 the organ was endangered by the tin pipes requisition. The requisition was enacted by the ministerial ordinance from the 29 October 1917 and the Prague's diecesis statute from the 19 December 1917. According to these orders, it was possible to exclude the instruments historically or artistically valuable. Two standpoints were considered. The most important was the standpoint musically technical, which was appreciated by experts named by the ministry of culture and education. For Prague, Dr. Dobroslav Orel was chosen. The second standpoint was the historical one and was appreciated by the provincial conservators. Normally, the two standpoints were considered concurrently in the case of organs built before 1850. Newer instruments were often considered unusable without principal. In those times, prof. Orel saved the St.Stephan's church as well, quotation from his review is the following:

„Rieger, Krnov - concert organ; nice tone, irrepparable".