The Neurocalometer

Origins

Laboratory work on the device began in 1920, according to a report in the Omaha Bee of 14 September 1924, later reprinted in Palmer’s Fountain Head News. The same report said the invention was brought to Palmer’s attention in April 1923, and that he and Evins then worked together to refine it.

Evins’s name is on the patents. On 18 January 1924 he filed United States patent 1,552,284, “Process of Spinal Analysis,” granted on 1 September 1925. The specification describes a method of “comparing the simultaneous temperatures of separated areas along the spine.” A second patent, 1,610,271, “Temperature Detector,” was filed on 25 August 1924—the day after the Lyceum address—and granted on 14 December 1926. A half interest in both was assigned to Frank W. Elliott of Davenport. The Palmer School announced that it held the exclusive right to manufacture and sell the instrument, under licence from Evins, in the United States and sixteen other countries.

Palmer did not wait for the formal unveiling to put the instrument into use. He later wrote that deliveries to the field began in June 1924. In a 1992 letter, the historian Joseph C. Keating noted that the NCM had been in use in the field for several months before the Lyceum.

Timeline

1. 1920

   Evins begins laboratory work on the instrument, according to the Omaha Bee.

2. April 1923

   The invention is brought to B.J. Palmer’s attention.

3. 18 January 1924

   Evins files the “Process of Spinal Analysis” patent.

4. June 1924

   Palmer later dates the start of field deliveries to this month.

5. 24 August 1924

   Official introduction at the Palmer School Lyceum in Davenport. Palmer’s address is published as The Hour Has Struck.

6. 25 August 1924

   Evins files the “Temperature Detector” patent.

7. 14 September 1924

   The announced lease price rises to $2,200.

8. 18 October 1924

   Palmer reports that more than a thousand instruments are in use.

9. 1925–1926

   Senior Palmer faculty leave the school. In August 1926 they help establish Lincoln Chiropractic College in Indianapolis.

10. Early spring 1930

    Palmer announces the Hole-in-One (HIO) upper-cervical idea. In his later practice the NCM was one of the instruments used in that analysis.

How it worked

Mechanically, the Neurocalometer was a differential thermometer. Evins’s patents describe a handpiece with two contact points, or “junctions,” spaced apart and connected to a sensitive galvanometer. The preferred construction used a thermopile: several thermocouples of dissimilar metals, such as copper and constantan, connected in series so that a small temperature difference would produce a readable current.

When the two junctions were placed on corresponding areas on the left and right sides of the spine, the galvanometer needle stayed at zero if the temperatures were equal, and swung toward the warmer side if they were not. The size of the deflection indicated the size of the difference. The patents also allowed the handpiece to be turned so that the two points could compare areas spaced along the length of the spine, and they described a combined form in which the dial and the contact arms were built into one casing.

A contemporary description reprinted in Keating’s chronology matches that design: a small two-branched detector, with a left and a right contact, joined by a cord to a recording box whose scale corresponded to the two sides. Readings could be noted on a chart as the examiner moved along the spine. The same account called the instrument “a self-generating heat-recording device, indicating heat differences on a galvanometer,” and said it was not operated by an external electrical supply. Thermocouples generate their own small current from heat.

Palmer presented those readings as a way to locate what he called “nerve interference” or subluxation, and to decide when an adjustment had been made. In the Fountain Head News of 9 August 1924 he wrote of the NCM as “the most valuable invention of the age because it picks, proves and locates the cause of all dis-eases of the human race.” Those were promotional claims of the period. They are recorded here as part of the historical record, not as statements of fact about the body or about treatment.

The lease

The Neurocalometer was not sold. It was leased, on a ten-year contract, and manufactured exclusively by the Palmer School under Evins’s licence. The school would not deliver an instrument until the lessee had completed a two-day technique course, “morning, noon and evening,” with the device and a patient (Fountain Head News, 26 July 1924).

The price rose quickly, and the rises were public. In the Fountain Head News of 2 August 1924 Palmer wrote that when the instrument was first presented “down East,” a price of $500 was thought “pretty stiff, but it was worth it.” It then rose to $600, “and some resentment,” then for a short time to $750, “and then the storm burst loose.”

“The price after midnight of September 14th will raise to $2,200, or an increase of $700. The terms will then be $200 cash and $100 a month until $1,000 has been paid, at which time you will be entitled to your technique and your Neurocalometer.”

Keating, working from the Fountain Head News, later reconstructed the official sequence as $500 before the Lyceum, $1,500 at the 1924 homecoming, and $2,200 by 14 September 1924. On 25 October 1924 Palmer announced that the lease would probably rise again, to $3,000, by 1 January 1925.

The contract also fixed a minimum fee. If a lessee charged for a reading, the charge could not be less than $10 (Fountain Head News, 11 October 1924).

The rupture

The combination of a restricted lease, a rapidly rising price, and Palmer’s insistence that the instrument should be central to practice divided the profession.

The disagreement was not necessarily visible in the Lyceum hall itself. Keating later concluded that the meeting was probably not a scene of open discontent: Harry E. Vedder, one of the school’s senior instructors, introduced Palmer that day, and in October 1924 Palmer announced that Vedder, James Firth, Stephen J. Burich and Ernest A. Thompson—known as the “Big Four”—had themselves taken leases. Keating suggested that the later faculty revolt had more to do with subsequent limits on academic freedom than with the speech alone.

The departures followed over the next two years. Thompson, who had headed the school’s spinography department, was the first significant loss and later settled in Baltimore. Firth’s departure was announced in October 1925. Burich and Vedder’s resignations, effective 15 May 1926, were reported in the Bulletin of the American Chiropractic Association under the heading “P.S.C. Loses Its ‘Big Four.’”

In August 1926 a new, non-profit school, Lincoln Chiropractic College, was chartered in Indianapolis, with Vedder as president. Classes began on 20 September in rented rooms in the Lumberman’s Insurance Building. The founding faculty were Vedder, Firth, Burich and Arthur Hendricks, all former Palmer instructors. Thompson later served on Lincoln’s board of trustees. The historian C. C. Stowell has argued that Palmer’s later imposition of NCM and Hole-in-One theory on his faculty, which Stowell treated as a breach of academic freedom, may have had much to do with the break. Lincoln College remained open until 1971.

The effects reached the national associations as well. The American Chiropractic Association of the 1920s, founded in 1922 as an alternative to Palmer’s Universal Chiropractors’ Association, grew after the NCM’s introduction and a decline in UCA membership. After Palmer left the UCA, the two societies began talks that produced the National Chiropractic Association in 1930.

Rival instruments appeared almost at once. In August 1924 Evins, acting for the Palmer School, threatened legal action against firms the school regarded as infringers, before the American patents had even been issued.

Legacy

In the early spring of 1930 Palmer announced the principle he called Hole-in-One: that a subluxation, as he then defined it, could exist only in the occipito-atlanto-axial region at the top of the neck. According to A. A. Dye, the upper-cervical idea had already been “in the air” at the Palmer School in the late 1920s. In Palmer’s hands, HIO analysis used four things: the Neurocalometer, the spinograph (the school’s spinal X-ray), a toggle-recoil adjustment, and the knee-chest table. Palmer made upper-cervical work the core of the school’s programme for about two decades. In 1935 he looked back to the 1930 announcement and restated the claim in uncompromising terms. That later programme is part of the NCM’s story because the instrument, introduced six years earlier, remained one of the tools with which he argued the case.

The NCM also left a line of later instruments. Researchers have described it as the predecessor of the Nervoscope, a contact thermocouple device still associated with the Gonstead technique. From the 1920s onward, other paraspinal thermographic instruments—including devices that recorded a continuous trace of left-to-right temperature difference as the probes were moved along the spine, and, later, infrared methods—continued the same basic project: measuring skin-temperature patterns along the back.

The Neurocalometer itself was still being serviced at Palmer College into the early 1990s. In a 1991 interview recorded by Keating, a long-serving member of the school’s instrument-repair department said that new lease contracts had only recently ceased to be issued.

What the 1924 episode changed most clearly is not a matter of instrumentation. It marked a turning point in Palmer’s authority within the profession, helped to found a rival school, and left a documentary trail—patents, addresses, prices, resignations—that historians still use to understand a profession in the making.

References

1. Keating, J. C. “Introducing the Neurocalometer: a view from the Fountain Head.” Journal of the Canadian Chiropractic Association 35, no. 3 (September 1991): 165–178. PMC2484664.
2. Keating, J. C. Chronology of the Neurocalometer. Phoenix: National Institute of Chiropractic Research. Includes contemporary quotations from the Fountain Head News, Palmer’s 1924 address The Hour Has Struck, and the Omaha Bee of 14 September 1924 (reprinted 11 October 1924). PDF at chiro.org.
3. Keating, J. C. Letter to the editors, 27 April 1992, later circulated in connection with the Chiropractic Journal of Australia. Reconstructs lease prices from the Fountain Head News and quotes the April 1926 announcement “P.S.C. Loses Its ‘Big Four.’” PDF at chiro.org.
4. Keating, J. C. “Lincoln College: A Glimpse at the Early Years.” Account of the 1926 founding of Lincoln Chiropractic College in Indianapolis by former Palmer faculty. PDF at chiro.org.
5. Keating, J. C. “The Short Life & Enduring Influence of the American Chiropractic Association (1922–1930).” On the ACA’s growth after the NCM introduction, the decline of UCA membership, and the later formation of the National Chiropractic Association. PDF at chiro.org.
6. Evins, Dossa D. “Process of Spinal Analysis.” U.S. Patent 1,552,284, filed 18 January 1924, granted 1 September 1925. Assignor of one-half to Frank W. Elliott. Google Patents.
7. Evins, Dossa D. “Temperature Detector.” U.S. Patent 1,610,271, filed 25 August 1924, granted 14 December 1926. Assignor of one-half to Frank W. Elliott. Google Patents.
8. Nash, Jetta. “In the eye of the storm: Dossa Dixon Evins and the neurocalometer debacle.” Chiropractic History 15, no. 1 (June 1995): 23–26. PMID 11613387.
9. Martin, Steven C. “Chiropractic and the Social Context of Medical Technology, 1895–1925.” Technology and Culture 34, no. 4 (1993): 808–834. doi:10.1353/tech.1993.0007.
10. Cooperstein, Robert. “Upper-Cervical Technique, Historically Considered.” Journal of the American Chiropractic Association (March 2003). Cites A. A. Dye on the late-1920s background and the early-spring 1930 announcement, and describes the four elements of HIO analysis in Palmer’s hands. chiro.org.
11. Young, Kenneth J. “Evaluation of Publicly Available Documents to Trace Chiropractic Technique Systems That Advocate Radiography for Subluxation Analysis: A Proposed Genealogy.” Journal of Chiropractic Humanities 21, no. 1 (2014): 1–24. Includes Palmer’s 1935 restatement of the 1930 Hole-in-One announcement. PMC4245702.
12. Mansholt, B. A., R. D. Vining, C. R. Long, and C. M. Goertz. “Inter-examiner reliability of the interpretation of paraspinal thermographic pattern analysis.” Journal of the Canadian Chiropractic Association 59, no. 2 (June 2015): 157–164. Describes the Neurocalometer as the predecessor of the Nervoscope used in the Gonstead system. PMC4486995.
13. “Advances in Paraspinal Thermographic Analysis.” Historical sketch of dual-thermocouple paraspinal scanning from the Neurocalometer onward, and of later thermographic methods, compiled at chiro.org.

Primary quotations from the Fountain Head News and from The Hour Has Struck are taken from the texts assembled in Keating’s Chronology of the Neurocalometer and from his 1991 and 1992 papers. Patent descriptions are taken from the granted specifications.