Shop Orders, Job Numbers, Contract Numbers, and Other Non-Opus Identifiers

Sources use at least four different terms for a builder’s instrument number: “Opus,” “Job number,” “Organ number,” and a bare “No.” on its own. The Organ Historical Society’s Historic Pipe Organ Registry application uses the first three side by side; as of September 1, 2026, it asks for the builder or builders, the instrument’s date or dates, and “any Opus, Job or Organ number assigned to the instrument.” The form does not treat these as one thing with three names; it leaves room for whichever class the builder used. A dealer’s used-organ listing shows the plainest case, designating a McManis organ, given the year 1957 in the listing, simply as “No. 36” and stating its later location uncertainly, so the number arrives with no class label at all.

The practical rule is to carry the term with the number. Write down “Job 1661” or “contract 1885” as the source gives it, rather than converting it to “opus” in your notes, because the conversion is where the evidence gets overstated. Examples like these establish how the evidence behaves; they do not prove anything about a particular instrument without that instrument’s own records and physical evidence.

One number gets two names when a publication and a builder describe the same numbering context in their own vocabulary. The Diapason’s 2007 cover feature on Austin Organs calls number 1885 the original Austin company’s final “contract,” while the manufacturer’s own searchable list on austinorgans.com heads the same column “Opus #.” Both are describing one series. Neither establishes a rule that “contract” and “opus” are interchangeable everywhere, and the sensible reading is that they are two labels for one Austin sequence, not two different numbers.

Holtkamp shows the same split between a database and a firm. As of September 2, 2026, the Organ Historical Society Pipe Organ Database titles Holtkamp records with builder, number and year under the word “Opus,” for example “Holtkamp Organ Co. – Opus 2092, 2007,” whereas the firm’s own published job chart labels the same series “Job Number.” That mismatch sits at the level of the record title, not the database’s internal field labels, and it shows only that the two sources name the series differently, not that they are counting different things. Kimball pipe-organ numbers of the 1920s and 1930s carry a “KPO” prefix in some published accounts and a bare “Opus” in others, and none of those accounts says whether “KPO” was Kimball’s own factory notation or a convention adopted later by researchers and restorers; until a factory document says otherwise, treat the prefixed and unprefixed forms as one series. Whether a firm’s own table is an opus list and how to read its columns is the job of How to Read an Organbuilder Opus List.

Some firms assigned no opus numbers at all and identified their instruments by job number. The clearest documented case is Holtkamp. An editor’s note in the Organ Historical Society Pipe Organ Database, read through a third-party mirror of the database, states: “Although neither Votteler-Holtkamp-Sparling nor their successor Holtkamp Organ Co. assigned Opus numbers to their instruments, this organ was identified in factory documents as Job number 1661.” A second record repeats that neither firm assigned opus numbers and that the job number stands in for one in the database. This is an editor’s note rather than a factory publication, but it is explicit and repeated. The consequence for a reader is direct: an “opus” search in that database returns Holtkamp records headed “Opus” while the underlying identifier is a job number, and the firm’s own chart uses the job-number vocabulary.

The English Hope-Jones firm is another job-numbered case. The order book held in the British Organ Archive records Hope-Jones job numbers 1 to 98 for 1892 to 1896, which is a job series rather than an opus series of the kind Wurlitzer later used. That reading is inferred from the archive handlist’s description of the order book; the firm’s practice after 1896 and beyond job 98 is not established by it. Two firms do not tell you how many firms numbered work this way. They tell you to check the numbering class before you assume an opus series exists.

A job number can survive a change of corporate name, because it belongs to the shop’s count rather than to the company’s title. Holtkamp job numbers run continuously across the 1951 renaming: The Tracker for October 2019 cites Job No. 1571 (Brunnerdale Seminary), Job No. 1580 (the Cleveland Museum of Art addition) and Job No. 1602 (Saint James Episcopal) under the Votteler-Holtkamp-Sparling name, and database records give Job 1659 (Syracuse University, Hendricks Chapel) and Job 1661 (College of Wooster) under Walter Holtkamp and Holtkamp Organ Co. That continuity is assembled from two sources rather than read from a factory job book, and the sources do not state where the series began, whether it started under Votteler, or whether any number was ever reused. So a job number can place an instrument in the firm’s sequence across the renaming, but it does not by itself tell you which corporate identity signed the contract or when.

What the job number does not survive is the loss of the paper behind it. Factory documentation of the Holtkamp job series is attested only indirectly, through database editor notes saying the organ “was identified in factory documents as Job number 1661,” which asserts that factory documents were consulted without naming, dating or locating them. That note concerns the mid-twentieth-century job series and does not show that comparable documentation survives for the earlier Votteler-era partnerships. A job number with no located job book behind it is an index entry, not a file.

A job number can be reassigned when an instrument moves, so one instrument can carry two job numbers in the same firm’s series. The database record for the College of Wooster instrument gives Job number 1661 and adds “Job No. 1877 after 1971 relocation” to McGaw Chapel. That is a single record, and no source says whether renumbering on relocation was Holtkamp’s general practice, so the lesson is a caution rather than a rule: if a firm’s number for an instrument does not match the number in an older record, a relocation or later job is one explanation to test before concluding that two different instruments are involved. A second job number issued by the same firm for later work is a different thing from a rebuild plate or a rebuilder’s own opus number, which are handled elsewhere among the numbers-and-dates pages.

A shop order is the contemporaneous factory record of what the shop was told to build. For Estey pipe organs, the catalog record of the shop-order series contributed by the Organ Historical Society Library and Archives describes shop orders “with pipe scales, stop lists, console and blower specifications and voicing instructions.” That is fabrication-level detail about the instrument as built, not a contract summary. The description is a cataloger’s summary of a series rather than an inspection of individual orders, so it does not establish that every shop order carries all four kinds of content, and it says nothing about whether shop orders record later alterations.

Coverage is partial. As of September 2, 2026, the Estey Organ Museum states that “Shop Orders exist for about 2/3 of the organs, as do correspondence files for most Estey pipe organs,” adding that pipe organs “created a greater amount of paperwork” than reed organs. For roughly a third of Estey pipe organs, then, no contemporaneous shop order should be expected, and “most” for correspondence files is not quantified. Those are the museum’s estimates about the body of records, not counts from a processed finding aid.

A shop order is retrieved by opus number only where the repository has built that index, and that is a property of the repository, not of the record. For Estey, the same catalog record states that the shop-order files “are in a searchable database by opus number, date, institution, city and state,” so an opus-number index to Estey shop orders exists as a repository finding tool. The database is described in a catalog note, its currency and coverage are unstated, and it is not described as covering every Estey opus number; it does not appear to be offered through any public search page as of September 2, 2026, so an enquirer reaches it through the repository.

Hook & Hastings shows the opposite condition, where a production number exists but no opus index does. The Organ Historical Society’s Hook and Hastings introduction states that “the official records and documents of the firm are lost,” and names as substitutes the firm’s own publications from 1857 to 1936 containing “their opus list, sample stoplists, and testimonial letters,” newspaper and journal reviews of recitals and dedications, and correspondence and financial records held in individual church archives.

Historic New England’s collection-level description, by contrast, records a Hook & Hastings Company collection, CC007, of 0.42 linear feet in one legal-size document case, dated 1869 to 1969 with the bulk between 1869 and 1931, donated in 1955 by Anna Hall, niece of Frank H. Hastings, and containing “a company record book in which nearly every organ the company built is listed alphabetically by location.” Its item-level description of that record book says it was begun about 1885 and gives location, venue, production number, installation date and specification for organs built between 1829 and 1920, with “nearly every” being the repository’s own qualification of a single manuscript volume compiled retrospectively. The two positions are best read together as meaning that the main body of shop records did not survive as a single archive while one small collection of company material did; a box of 0.42 linear feet supplements the material held elsewhere rather than replacing a company archive.

For a reader holding a number, the operative point is arrangement. The record book records a production number rather than an opus sequence and is arranged alphabetically by location, and Historic New England’s online description publishes no opus index, concordance or item-level list; the file-level records carry titles, dates and folder numbers only. Whether a production number written in the book equates to a published opus number is unestablished, because the online description does not say and the volume would have to be read to settle it. A researcher who has only an opus number therefore needs a published opus list or a location before this collection becomes usable.

Different record classes for the same instrument carry different authority, and the shop order sits closest to the work. For an Estey pipe organ, four classes of evidence can distinguish original work from later change. Two are company records now at the Organ Historical Society: the shop order made at the time of construction, surviving for about two thirds of instruments, and the per-instrument correspondence file, surviving for most instruments and containing drawings, blueprints and telegrams. The other two are the published opus list derived from cost cards, which is secondary and whose compiler defers to the shop orders, and physical evidence on the instrument itself. No single source ranks these four, the physical-evidence entry rests on the general practice of opus marking rather than on an Estey-specific statement, and none of the sources says which class settles a dispute when two disagree.

The cost card is the record class that the published Estey list quotes, and it behaves like a per-instrument factory card recording the customer or destination and sometimes a specification detail, amended over the life of the record. List entries quote it directly: Opus 299, where “St. Louis Store” was on the original cost card and is crossed out; Opus 675, “with Piccolo” on the cost card; Opus 2217, cost card blank with “B. P. O. E. Lodge” crossed out on a later list; Opus 2587, “Chapel” on the cost card; and Opus 1637, where the cost card reads “St. Paul’s A.M.E. Church, Wichita, KN, not sold.”

These are quotations inside a compiled list, not the cards themselves, which are held at the Organ Historical Society and are not published; six instances out of 3,261 entries characterize the class without describing a standard card layout, and the crossings-out show revision without dating it. A number that leads to a cost-card entry has led to a summary that was itself corrected over time, which is one reason the list’s compiler defers to the shop order. Reading the columns and qualifications of a published list is the job of How to Read an Organbuilder Opus List.

A serial number from a reed organ, a piano or a blower belongs to a different series and will not retrieve a pipe-organ record. The Estey Organ Museum’s guidance for reed organs states that “the 3-digit and 4-digit numbers stamped into the top rail are not serial numbers” and that “the serial number has 5 or 6 digits,” so on an Estey reed organ a short stamped number is not a dating number. That warning is stated for reed organs only; the museum’s material carries no comparable statement for pipe organs.

As of September 2, 2026, the museum’s restorer resources page keeps reed-organ dating and pipe-organ identification under separate headings: reed organs by serial number, converted to a date through the Gellerman chart; pipe organs by opus number through the downloadable opus list and the Organ Historical Society database. The page nowhere says in terms that the serial chart does not apply to pipe organs. The separation is structural, and the inference that a reed-organ serial chart cannot date a pipe organ rests on that structure and on the different numbering series.

The Kimball case shows the trap by magnitude. In the same period, Kimball reed-organ serials ran to 403,690 by 1922 and piano serials stood at 322,000 in 1920 and 383,000 in 1930, while Kimball pipe organs recorded for 1924, 1930 and 1931 carry four-digit numbers: KPO 6763, KPO 7073 and KPO 7066. The piano and reed-organ serial tables behind those figures do not mention pipe organs at all. The contrast rests on the size of the numbers rather than on any statement that the two series are unrelated, which makes it strong enough to warn against feeding a four-digit pipe-organ number into a piano serial chart and not strong enough to say how Kimball actually assigned its pipe-organ numbers.

A blower serial number is the weakest strand of all, because no corroborating record series is known for it. As of September 2, 2026, no published register, index or lookup service for organ blower serial numbers of any make had come to light, and the society, venue, museum and archival records that identify instruments do not carry a blower number as a field. That is a limit on what is known rather than proof that no such series survives.

The one list that does use blower numbers as a field is a private reconstruction. The Robert Morton opus list maintained by Greg Rister is indexed by state and city with columns for location, size, year, blower number, opus number and notes. It is built, in its compiler’s words, from “the RM opus list from Junchen’s Encyclopedia as a starting point, but adding things from other sources as they become available,” is hand-entered and incomplete with many entries marked “????,” and by its own statement was last updated 5/9/2019. Because it is a reconstruction from a secondary encyclopedia plus contributed information rather than a factory list, a blower number matched there dates an entry in that reconstruction, not the instrument.

One company can run two numbering series of entirely different scale, and the scale can tell you which line a number belongs to. A compiled Estey reed-organ page states that from around 1850 the company produced “some 520,000 organs, large and small, in all sizes, shapes and designs,” a figure that counts the reed-organ line, while the pipe-organ department is recorded at roughly 3,261 opus entries. Both figures are secondary compilations, and they are not comparable quantities: the reed-organ figure is a production total for shipped instruments numbered in a serial sequence, and the pipe-organ figure is an opus count that includes rebuilds. An Estey reed-organ serial number runs to five or six digits, while the pipe-organ opus count is of a different order, in the low thousands, so the size of the number is the first sorting test. How an opus count relates to the number of instruments a firm actually produced is a question for the opus-list page rather than this one.

Which firm’s series a number belongs to is a different question again. When the same number turns up under two builders’ names, that collision is the subject of Why Two Builders Can Share the Same Opus Number, and it is not resolved by the size of the number.

Whatever the number, record three things before you search or hand it to anyone else: the term the source attached to it, the series or record class it belongs to, and what the record it retrieved actually says. Those are what a registry form asks for, and what an archivist or a technician will want to know, and they keep a number from doing more evidentiary work than it can carry. The examples here establish what each kind of evidence can and cannot settle; deciding what a particular instrument is still takes that instrument’s own records and its physical evidence.