Ian D. Fowler

Uhrenrestaurator und Uhrenhistoriker


Review of Jürgen Ermert's new book, Volume 3 of

"Präzisionspendeluhren in Deutschland von 1730 bis 1940.
Observatorien, Astronomen, Zeitdienststellen und ihre Uhren

Precision pendulum clocks in Germany from 1730 till 1940.
Observatories, astronomers, time systems and their clocks,

published by JE Verlag: Christian Pfeiffer-Belli (Ed.), Doris & Gerth Herold, Jürgen Ermert.
Distributed by Versandbuchhandlung Doris Herold, Am Kühlchen 13, D-41516 Grevenbroich,

464 pages, ca. 1100 illustrations mainly in colour. Standard edition € 146,- + postage, deluxe edition bound with linen covers and a genuine leather back € 226,- + postage.

1. The Book and its binding.

Volume 3, which deals with the precision pendulum clocks made in Glashütte, is the first of the 4 volumes to be published and coincides with the 160th anniversary of Professor Ludwig Strasser's birth and its celebration in Glashütte in December 2013. The majority of precison pendulum clocks with Glashütte signatures are associated with the firm of Strasser & Rohde although there are other notable makers as Ermert relates.
If not so well known in other countries Glashütte is for German horologists the epitome of precision horology, noted especially for the gold pocket watches made by the firm of Lange & Söhne in the second half of the nineteenth and beginning of the twentieth century; later also for the tourbillons made in the horological school under the direction of Alfred Hellwig and also military watches and chronometers for the Second World War. It is a small town in the Erzgebirge in the south eastern part of Saxony some 30 miles from Dresden. Since the fall of the iron curtain in 1989 it has regained its status as a Mecca for watchmaking.
There are now some 20 firms selling watches, at least two of which  Lange und Söhne, and Glashütte Original  produce their own movements on site. The extensive museum housed in the building of the old school is a magnet for tourists. Glashütte has always had a staunch fan club of patriotic (to use but one word) watch collectors and experts, who seem very well informed. It is, to a certain extent, a closed shop and newcomers are regarded with apprehension. It is into this lion's den that Jürgen Ermert dared to enter when he realised that it included an integral part of German precision horology with which he too had to occupy himself. Fortunately he could engage the help and approval of a friend, Kurt Herkner, who was the first to publish a comprehensive work on Glashütte clocks and watches in 1978: Glashütte und seine Uhren, Kurt Herkner, Dormagen. Since then there have been numerous articles and books relating to Glashütte although the precision pendulum clocks in the more general works tended to take second place. Klaus Erbrich's book on precision pendulum clocks in 1978, which is still sought after avidly even in England, includes some Glashütte examples. Hans-Jochen Kummer's informative yet entertaining book on Ludwig Strasser published in 1994 deals more with the person Strasser, but includes an appendix by Professor Herbert Dittrich, who describes the more technical details of the clocks themselves although the photographic material is somewhat lacking. Reinhard Meis' two volume edition of  A.Lange & Söhne published 2011 illustrates some Glashütte examples. The volume of Derek Robert's Precision Pendulum Clocks on non-English clocks devotes a chapter to German clocks (in a weird backward chronological order) and includes a number of Glashütte examples with some explanation to the technicalities presumably supplied by Professor Dittrich and Christian Pfeiffer-Belli.
Helped by his background in the IT industry Jürgen Ermert has been able to make exhaustive use of the material readily available in the internet which has been uploaded by university libraries and other institutions nationally and internationally, not to mention Google ebooks and Wikipedia. Thus much traditional academic research by having to visit libraries in person could be spared. He has endeavoured to include as many detailed photos of the technical details of the movements as possible where available. To this end he engaged the help of clock owners, restorers, dealers and auction houses and even some museums, who provided material free of charge. It must be added that other museums wanted to charge extortionately for their so-called rights. (The reviewer would like to apologise at this point for the quality of the photos he provided with the excuse that he had never expected anyone would want to publish them.)
Emphasis is made that the subject matter of the books is precision pendulum clocks in Germany and not just German precision pendulum clocks.

2. Glashütte in Saxony (second half 19th century)

Volume 3 begins with an eleven page index of the contents of all four volumes: -

Volume 1
  • Astronomical pendulum clocks from 1730 until 1770 in/ for Germany (i.e. the German speaking countries) including examples by Graham, Shelton, Mudge and Dutton.
  • Clocks in the observatory in Leiden (Holland).
  • Development in the observatories in Vienna and Prague; German movements based on clocks by Graham such as the presumably earliest German precision pendulum clock by Philipp Vötter in Vienna.
  • Astronomical pendulum clocks in Germany from 1770 until 1840 (Part I),
  • Important astronomers and their observatories in eigthteenth century Germany,
  • The development of the early German precision regulator until 1840,
  • A survey of the clocks in the observatories and time systems in Germany from 1730 till 1830,
  • The technical influence of English horology in German observatories in the eighteenth and nineteenth centuries,
  • John Arnold and Son,
  • Benjamin Vulliamy, clockmaker by appointment to George III.
  • The first clocks in the South German provinces e.g Freiburg im Breisgau and Eichstätt from 1775.
  • An astronomical longcase clock with year duration by Johan Michel Dermer, Ochsenhausen.
  • The precision pendulum clocks of Peter Kinzing in Neuwied from 1780.
  • Peter Bofenschen in collaboration with Breguet and Kinzing, by appointment to the King of Hannover.
  • German clocks made in the technical style of Arnold by Klindworth in Göttingen and Auch in Weimar.
  • Appendices 1 with details of original clocks by Graham and Shelton in comparison to existing copies, and 2 with details of originals clocks by Arnold  in comparison to existing copies. Biography and sources. Index. Advertisements.

Volume 2
  • Astronomical pendulum clocks in Germany from 1770 until 1820.
  • Early precision timekeeping in Dresden from 1783 with examples by Köhler, Seyffert and Schuhmann.
  • Joseph Weidenheimer in Mainz.
  • An anonymous longcase clock about 1790 from the area around Hessen and Frankonia.
  • The clockmaking family Roetig in Hachenburg and a regulator by Friedrich Wilhelm Roetig 1800.
  • Johann Georg Repsold, an astronomical instrument maker and the first maker of precision pendulum clocks in Hamburg.
  • French observatory precision pendulum clocks exemplified by a clock by Louis Berthoud in the Royal observatory in Bogenhausen (Munich) from ca. 1807.
  • Joseph Utzschneider's optical and mechanical institute,
  • South German precision pendulum clocks by Liebherr and Mahler ca 1808. 
  • Johann Wilhelm Gottlob Butzengeiger in Tübingen from 1810.
  • Josef Geist in Graz from 1816.
  • Johann Christian Friedrich Gutkaes, clockmaker by appointment to the Saxon court and the movements with an inverted escapement from 1820.
  • A precision pendulum clock made in Stuttgart by Leonardt Kraut ca. 1825/30 in the manner of Philipp Matthäus Hahn.
  • Christian Friedrich Zachariä Leipzig and his clock Nr. 6 with year duration and the later master clocks by Berhard Zachariä.
  • Chritian Friedrich Tiede in Berlin, maker of astronomical clocks by appointment from 1826.
  • Heinrich Johann Kessels,s a European precision clockmaker from c. 1828.
  • 30 other examples of precision clocks and their makers.
  • Appendix, Biography, Sources and References, Index

Volume 3 (see below)

Volume 4
  • Astronomical Pendulum Clocks in Germany from 1840 until 1940 (Part 2)
  • Theodor Knoblich in Altona, chronometer and precision pendulum clockmaker from 1863.
  • Ferdinand Dencker in Hamburg, chronometer and precision pendulum clockmaker from 1866.
  • Adolph A. Kittel in Emden and Altona, chronometer and precision pendulum clockmaker from 1868.
  • Max Matthäus Ort and other makers in the Nuremberg/Bamberg area.
  • Sigmund Riefler - the art of engineering versus the art of horology from 1890 onwards.
  • Karl Sartori, his precision workshop for clockmaking in Vienna from 1912.
  • Walter Cloos and his workshop, precision pendulum clocks from Würzburg from ca. 1927.
  • 38 other examples of German astronomical pendulum clocks from 1840 onwards with information to the makers.
  • Summary, Appendices. Explanation of terminology, bibliography and references, index etc.

3. Some examples of the layout.

Volume 3 continues with a greeting by Stefan Muser, proprietor of the renowned auction house Dr. Crott in Mannheim, who has sold many precision pendulum clocks, some of which are illustrated.
The author provides a 5 page foreword explaining his point of view and methodology.

The first short chapter (pages 26 -40) is a general introduction to the disparate subject matter leading to the development of a standard German precision pendulum clock by the beginning of the twentieth century. The illustrations intended to whet the appetite include the dismantled movement of probably the oldest clock by Vötter in Vienna in the style of Graham, the oldest longcase regulator by Köhler in Dresden used as a master clock, the ornate barock dial of a clock by Wisnpaindtner in Eichstätt dated 1775 (now in the clock museum in Furtwangen), a Neuwied regulator of around 1780-90 more in the French style, the standard time reguator for the city of Berlin made by Christian Möllinger in 1787, as well as more typical examples by Thiede, Knoblich, Riefler and the Furtwangen horological school. There is a list of the more important German clockmakers arranged chronologically according to their date of birth. An old photo of the port of Hamburg from the beginning of the twentieth century shows a time ball along with a drawing of the old time ball from 1901. One must bear in mind that accurate timekeeping for marine purposes did not play such an important role in Germany as in England or France until the rise of Kaiser Bill at the end of the nineteenth century. The early German precision clocks were used in astronomy, in time systems, geodesy, (and as shop regulators and showpieces for the richer members of society etc.- reviewer).

The second short chapter (page 41-52) is dedicated to a Hamburg chronometer and precision regulator maker Joseph Johann Ludwig Nieberg from Quakenbrück who invented a constant force escapement in 1846 and patented it in England where it was exhibited at the Great Exhibition in 1851. It was based on the principle of a gravity escapement. As yet there are no known examples by Nieberg still in existence, but it created quite a furore at the time and was described in numerous articles including Moritz Großmann's translation of Saunier's work. Großmann was situated in Glashütte, made watches, clocks and instruments and was one of the founders of the horological school there. As far as the reviewer can see this is the only connection Nieberg had with Glashütte, which hardly explains the inclusion of Nieberg in this volume rather than in volume 2. Despite this there follows a detailed description of a typical Nieberg clock with dead beat escapement and mercurial pendulum. There are excellent photos of the movement, pendulum and case, followed by a list of all the movement dimensions.

The story of clockmaking in Glashütte begins definitively in the next chapter (pages 53-187) entitled "Glashütte becomes a Mecca of  German precision (pendulum-) clockmaking" starting with the arrival of Ferdinand Adolph Lange in 1845 from Dresden and continuing until the formation of the central association of German clock and watchmakers under the auspices of Moritz Großmann resulting in the foundation of the German school of horology in Glashütte in 1878. (The building of the school is appropriately used today for the horological museum.) The students had to do practical work making clocks, watches, and tools. Some made precision pendulum clocks which are today much sought after collectors' pieces as they were obviously executed to the highest standards of workmanship. The standard precision pendulum clocks and their pendulums made by the students are comparable to those of Strasser & Rohde (covered in detail in the next chapter), but the movements were stamped Deutsche Uhrmacherschule Glashütte Sa. Various examples of clocks made in the school are shown in detail. Jürgen Ermert also shows other pieces of work such as electric clocks which were very much a novum at the end of the nineteenth century.

This chapter continues with accounts of 9 firms in Glashütte who produced precision pendulum clocks. The first firm mentioned of Wilhelm Horn is relatively unknown. It was founded in 1862 and made simpler weight driven wall clocks with wooden pendulum rods for the telegraph offices as well as the other instruments. Gustav Rohde, who was later Strasser's partner, managed the firm of Horn from 1870 till 1875.

Paul Stübner was employed 25 years by Strasser & Rohde before he set up his own firm making fine regulators, marine chronometers, half-seconds pendulum clocks for geodesic experiments, etc. Ermerts shows 5 clocks including a half-seconds pendulum clock and an early example in excellent condition with concentric minute and hour hands in an ornate case. The history and provenance of the clock can be traced back in full. Stübner used Riefler pendulums in his clocks. (The dead beat anchor escapement is traditionally referred to in German as the "Grahamgang", being named after the inventor. However, the form used in all these Glashütte models with steel and sapphire pallets set in a brass frame, should, according to de Carle and others, be more correctly attributed to Vulliamy, or in German "Vulliamygang". - reviewer) Stübner stopped working in his firm in 1936 and it was finally dissolved in 1942.

Ludwig Trapp took over his father-in-law's firm in 1892 using initially pendulums from Strasser & Rohde or Riefler. In 1912 he started making pendulums after a design by Pleskot, a teacher in the horological school, the rights to which he had acquired. Trapp also used a simplified version of Strasser's detached spring escapement by Georg Bley. There are detailed photos of the movements and pendulums.

Karl Wilhelm Höhnel opened a business in 1916 making initially precision pendulum clocks. It was said that he was supplied with pendulums by Riefler for all his clocks although the author has found this to be only partially the case. Presumably he made his own unsigned copies of Riefler pendulums. He stopped making precision pendulum clocks in 1921 and concentrated on producing domestic longcase clocks with striking, the dials marked with "Original Glashütte". A typical example is illustrated.

4. Lange's half-seconds regulator with a detatched spring escapement.
The name of Ferdinand Adolph Lange is inseparable from that of Glashütte although he is remembered more for the excellent watches. However, there are some clocks signed by him made either very early in Glashütte or even in Dresden in collaboration with his father-in-law Friedrich Gutkaes. Lange had been in Paris and worked with Josef Thadäus Winnerl whose form of gravity escapement with small sperical weights imparting an impulse to the pendulum he used in round movements with inverted trains (reminiscent of the French regulators - reviewer). Some of these movements also have a dead beat anchor escapement whereby the pallets are attached to the suspension spring thus disposing with the anchor arbor and fork. This variation is also attributed to Winnerl (or Breguet? reviewer). A half seconds pendulum clock once used as regulator in Lange's workshop with a detached spring escapement is also illustrated. Today it can be seen still working (!) in the Glashütte museum. The action of the escapement functions in a similar way to the gravity escapements. As well as abundant photographic material of the clocks and old pictures of Lange's workshop (showing the half seconds clock) and work books Ermert includes drawings and extracts appertaining to the escapements and Lange's life.

Moritz Großmann originated from Dresden and was encouraged to come to Glashütte by Lange, but had spent many years abroad in France, England, Denmark, Sweden and ultimately in La Chaux de Fonds until he finally settled there in 1854 opening a business making all types of watches, precision regulators, marine chronometers, models, micrometers etc. although signed examples of his work are not common. Among his many publications he established in 1879 the correct design of a pendulum clock with a seconds pendulum, ie. regulator - Die Anfertigung einer guten Pendeluhr mit Secundenpendel, which Jürgen Ermert refers to as Appendix 6 (in my edition it is Appendix 1 at the end of the book. Reviewer). This design was generally accepted by the other firms such as Stübner, Trapp, Strasser & Rohde etc. His pendulum design with a zinc tube was used by others including Strasser & Rohe until the introduction of invar and was referred to as the "Großmannsches Pendel".

Although there seems to be only one signed clock by Otto Lindig extant, which is described and well illustrated, he is warmly recommended by Großmann and there are advertisements of his firm and a price list for regulator parts supplied by him.

The next firm "Bahnzeit" (eng: Rail-time) in Glashütte has as yet been neglected in the history of clockmaking in Glashütte probably because examples of its work were not usually signed. Meis mentions the firm briefly with an old photo. The reviewer has encountered a few clocks of this kind over the years and associated them with Glashütte immediately, but been unable to name them. A typical example is illustrated in the book with details of the movement. A compensated pendulum according to Pleskot as in Trapp's clocks is used and an unusual form of impulsing the pendulum by means of a sort of short asymetrical crutch connecting with an extension to the lower suspension spring block. It is otherwise not seen in Glashütte.  It was employed by Breguet, but also described in an article by Victor Hoser in Budapest in 1912, which is reprinted here. These clocks mostly had a second train in order to activate contacts for slave clocks.

Hermann Goertz came to Glashütte as a refugee from Charkow at the end of the First World War at the age of 56 where he was given permission to complete a monumental astronomical clock in the school of horology where it still stands today in the foyer of the museum. He was commissioned in 1927 to make 12 precision regulators for Lange & Söhne to the highest standards possible (the dials thus being signed A. Lange & Söhne Glashütte Sachsen and not by Goertz ) although they were not all finished due to a debilitating stroke suffered in 1936. He used finer gearing and employed 2 forms of detached gravity escapements: the "bell gravity" (Glockenschwerkraft) escapement, an improvement of  the form used by Lange with small spheres (the spheres tended to stick whereas here the inside of the bell fell on to a sharp point), and the "claw gravity" (Klauenschwerkraft) escapement, which is in principle the same as Mudge's gravity escapement maligned by Grimthorpe. The "Glockenschwerkraft" escapement too is attributed by the Glashütte fans to Goertz, but, as Jürgen Ermert rightly points out, it was illustrated back in 1851 by J.P. Krüger in Berlin. Whether Goertz was aware that both of "his" escapements had already been invented is not known. Hellwig, who befriended Goertz, describes the escapements in detail in 1938 and also Goertz's later developments, which he could never realise, resulting in a detached spring escapement. This article is reprinted in appendix 9 of the chapter. Jürgen Ermert, quite rightly, does not deign to evaluate the efficiency of the escapements, but the reviewer has restored clocks with both types and found both to have deficiencies. (The inherent weakness of gravity escapements is where the gravity arms are pivoted as these bearings must be oiled. If not there is friction, but the oil will also gradually deteriorate effecting the running of the clock. reviewer)

There follows descriptions of 3 clocks. The first one with month duration with a separate calender and equation mechanism under the main movement in the manner of Brocot is attributed to Strasser & Rohde with some uncertainty. The second clock was in the office of the director of the school of horology and the author attributes it to Strasser & Rohde. The third clock belonged to Alfred Hellwig privately. Based on an unpublished text by Kurt Herkner the author gives a biography of Hellwig and a description of the clock. It was presented to Herkner by Hellwig's widow and daughter as recognition for his publications and commitment to Glashütte. As to be expected it is exceptional in that it incorporates ideas by Goertz and was probably completed by Hellwig using an ebauché (Rohwerk) by Goertz. There follows 10 appendices to this chapter with reprints relating to the school of horology, clock and watchmaking in Glashütte 1880, a visit describing Glashütte in 1901 by Ruffert, Pleskot's pendulum, examples of the presentation work of the students, Hellwig's article about Goertz's escapements, and a list of the firms in Glashütte (pre 1945?) compiled by Auction house Dr. Crott in 1991.

5. A four legged gravity escapement by Strasse & Rhode find Dietzschold / Karlstein.
The last chapter (pages 189 - 424), devoted to the firm of Strasser and Rohde, is justifiably the longest in the book as the majority of Glashütte precision pendulum clock were made by this firm founded in 1875. They also made other mechanisms, instruments and tools. After short biographies of the founders of the firm, Professor Ludwig Strasser and Gustav Rohde, and its subsequent history until 1958 the author presents an overwhelming number of clocks, especially earlier ones, too numerous to describe in a review. He includes reprints of contemporary advertisements and extracts from articles illustrating many technical details. Clocks were sold to observatories and institutes. The earliest and most of the later clocks had dead beat escapements although there is a clock in the school of horology in Karlstein / Austria with Grimthorpe's four-legged gravity escapement signed C. Dietzschold made by Strasser & Rohde in 1876.

(Dietzschold worked for a short time at the firm of Strasser & Rohde and was co-owner until he became the director of the new school of horology in Karlstein in 1879.) Although the firms of Strasser & Rohde and Riefler were competitors when it came to supplying the national observatories (e.g. in Potsdam) with regulators they corresponded with each other. It has been suggested, as the author relates, that Riefler's invention of the detached spring escapement prompted Strasser to invent a Glashütte alternative. His definitive version is the result of a clockmaker rather than of an engineer and equally good (if not better - reviewer. Although after the invention of his detached escapement Strasser did concede that the dead beat escapement was just as good!). For the first time Jürgen Ermert has been able to trace the development of this escapement. Misleadingly the first version was referred to as a gravity escapement by Strasser (Schwerkrafthemmung), which it is not. This is the first time that the precursor of the Strasser escapement has been discussed in horological literatur and copiously illustrated.

6. An early version of Strasser's detatched spring escapement erroneously referred to as a gravity escapement.

It is first mentioned around 1893. It has the modified pallets similar to the gravity escapements whereby the tooth of the escape-wheel falls first on the impulse face and is then locked (in the dead beat escapement it is vice versa). The asymetric crutch is attached to the pallet arbor with a short suspension spring. The axis of oscillation of the crutch spring is almost on the same level as the axis of oscillation of the pendulum suspension spring. Although there are a few working examples of clocks with this escapement extant (e.g. in the Astronomisch-Physikalisches Kabinett in Kassel) it must have been fickle, which is why at least one clock sold to the observatory in Leiden in 1898 was converted shortly after to the standard Strasser detached spring escapement. In this version Strasser employs a double suspension spring, the inner one suspending the pendulum and the outer one is impulsed by the anchor arbor via a frame with adjustable pin. He thus disposes of the crutch. The author reprints in appendix 6 of this chapter the correspondence between Strasser and Professor van de Sande Bakhuyzen in Leiden relating to this clock. Some clocks at this time were also equipped with electric contacts, even for seconds, and slave clocks in the manner of Hipp in Neuchatel were also made. Strasser & Rohde produced different types of pendulum, initially according to Großmann's design with a zinc tube and also mercurial pendulums. An overview is shown in appendix 1 of this chapter. After the introduction of invar steel, a steel and nickel alloy, by Guillaume not only Riefler (1897) but also Strasser & Rohde (1905) developed compensation pendulums exploiting the properties of this new material. However, Riefler's pendulums proved to be more accurate than Strasser & Rohde's so that clocks for observatories etc. were usually supplied with Riefler pendulums. The definitive form with 2 cylindrical weights is easily recognizable.

7 / 8. Strasser & Rhode showpiece floor standing regulator with an inverted detatched spring escapement.

Transportable half- seconds regulators for geodetic purposes and expeditions were also made, 6 of which are illustrated with details of the movements etc. including an unusual example with pendulum (by Riefler) beating 80 times per minute. In the 1920s the firm, now under new ownership, produced a small series of longcase clocks with visible inverted  Strasser escapements. These clocks were housed in stylish, expensive cases in the style of the era. They were intended as show pieces and not scientific instruments. (In fact the extended train to make the escapement clearly visible under the dial necessitates two extra wheels which vibrate and amplify unnecessarily the ticking of the clock. Reviewer). At the end of the chapter a coincidence clock by Strasser & Rohde is shown which was used to control a regulator and was set in motion by the telegraphic time signal.  (It can be roughly described as an acoustic vernier scale. reviewer).

There are 10 appendices to this chapter:
  • 1. A list (ca. 1910) of authorities, institutes and firms which were supplied with clocks by Strasser & Rohde for scientific purposes.
  • 2. An overview of the pendulums and an article in the Deutsche Uhmacher-zeitung 1906 describing Strasser's compensation invar pendulum.
  • 3. 4 publications describing the Strasser detached spring escapement.
  • 4. A reprint of a brochure advertising an astronomical regulator by Strasser & Rohde (ca. 1920)
  • 5. Instructions on how to set up a regulator (1920)
  • 6. The correspondence between Professor van de Sande Bakhuyzen and Strasser & Rohde
  • 7. A list taken from Hans-Jochen Kummer's book on Strasser (1994) and extended considerably by Jürgen Ermert
  • 8. A lecture by Professor Strasser on precision pendulum clocks and their adjustment
  • 9. Other instruments produced by Strasser & Rohde
  • 10. An extract from an article by Gustav Krumm (1920) comparing the Riefler and Strasser detached spring escapements.

There follows 3 general appendices (pages 425 - 439)
  • 1. A reprint of Großmann's article on the construction of a good quality pendulum clock with seconds pendulum including drawings of 2 examples of movement; one with a seconds dial as normal and one with centre seconds.
  • 2. An example of the use of precision pendulum clocks in the German research centres Berlin / Potsdam around 1910 with a list of the clocks.
  • 3. The introduction of standard time in Germany in 1880
The bibliography and footnotes are combined. They include standard literature, articles and many internet addresses. There is a general index, one of personal names , and one of place names.

9. A typical Strasser & Rhode shop regulator
The author is very generous with the photos so that some appear on more than one occasion (eg. the dial of the Dietzschold clock, diagrams of the gravity escapement with spheres used by Lange, details of the precursor of the Strasser escapement et al.). Some might find this confusing as it breaks the chronology in some cases, but it illucidates the text and avoids having to leaf through the book to find a reference to a photo. The footnotes relate to the sources whence information is taken. The author has quoted the sources very often directly in the main text and made this reasonably obvious although on some occasions some might find it tends to interrupt the flow of thought combined with the many photos and captions, which are, however, printed clearly in italics and in blue. The author has described the objects involved objectively and not tried to appraise the quality of the work, (which is very much to be advised when one considers the army of Glashütte fans who have been awaiting the book).

This book is a must for all those who have either a practical or theoretical interest in precision clockmaking and is highly recommended. The photographic material alone, especially of the technical details, justifies the price of € 146,- and anyone who has compiled such an opus knows the effort involved can never be rewarded monetarily.

We are looking forward to the next volume to be published whichever it might be.

Ian D. Fowler

Photos: by permission of Jürgen Ermert
Photo credits:
1. Jürgen Ermert
2. Deutsche Uhrmacher-Zeitung nr. 15, 1. August 1880.
3 / 4. Jürgen Ermert
5. Friedrich Harrer / Karlstein a.d. Thaya
6. Mhk Kassel (Michael Beck)
7 / 8. Ian Fowler / Friesenhagen
9. Ihno Flessner / Rastede

Ian D. Fowler
Am Krängel 21, 51598 Friesenhagen
Tel. +49 (0) 2734 7559
Mobil 0171 9577910

e-mail Ian.Fowler@Historische-Zeitmesser.de