ALRO Patent Slide Rules
This gallery is dedicated to the Dutch manufacturer ALRO who manufactured primarily quality circular slide rules in the in the Hague, Holland (Netherlands).
KEEP ISRM FREE!


ALRO Metal Case
"AL-RO" was founded by Ir. C.J. Dussel & A. Pasveer around 1931-1934. Their unique claim-to-fame was the metal case, which not only protected the slide rule in the field, but also acted as a stand for desktop use, Today, iPad covers mimic this approach that was developed in the 1930's. In 1959, the company decided to focus on inexpensisve plastic film slide charts and disks which could be sold for promotional items to corporations.

Read De Algemene 13cm Rekenschijven Van ALRO (2.16MB pdf in Dutch) on ALRO history written by Otto van Poelje in 2006.

See ALRO Timeline and 1050 Brochure at bottom of page.




HSRC0061 ALRO 100 R
ALRO 100 R
Generic disc of metal
125x135x115 mm
Front Scales: N2 N ( N N2 R N3 L )


HSRC3107 ALRO 1010 Bureau (desk) model
ALRO 1010 Bureau (deskk) model
Financial disc of metal
190x10 mm
Front Scales (Spiral) : 1) 2) 3)


HSRC0085 ALRO 1010 Commercial
ALRO 1010 Commercial
Log/financial disc of metal
125x135x12 mm
Front Scales: Scale from 1.000-10.000


HSRC0086 ALRO 1010 Commercial System Hatex
ALRO 1010 Commercial System Hatex
Log/financial disc of metal
125x135x12 mm
Front Scales: C ( D 1 )


ALRO PATENT System ALRO 200R

ISRM 13.01.26.01
ALRO PATENT System ALRO 200R
Made in The Hague, Holland
Dimensions: 125x135x12 mm
Patents No's (stamped on metal hub): USA 2,117,155; France 808,295; Gr. Britain 443689; Belgium 413,897; Germany 643,571; Holland 41,324
Front Scale
S, T, S&T, kW, N2, N ( N , N2, R, N3)
Cover Scale: Decimal/fraction, Log spiral scale
Acquired from the Netherlands, made possible by a gift from Robert L. Allison of Ballard, Washington.


REF ALRO 200R
ALRO 200R
Made in The Hague, Holland
Patents No's (stamped on metal hub): USA 2,117,155; France 808,295; Gr. Britain 443689; Belgium 413,897; Germany 643,571; Holland 41,324
Front Scale
S, T, S&T, kW, N2, N ( N , N2, R, N3)
Cover Scale: Decimal/fraction, Log spiral scale


Archive - This specimen belong to a Dutch mechanical engineer, Tony Krijnen, who used this in Burma in the 1930's in the oil fields of Bornea, Dutch East Indies . Tony died soon after WWII after being held prisoner in the Japanese camps in Java and Burma. Scan contributed by his son, Dr. H. John Krijnen, Netherlands


HSRC0077 ALRO 300 D
ALRO 300 D
Generic disc of metal
125x135x12.4 mm
Front Scales: L C COS ( D S N2 N3 LL3 LL2 LL1 )


HSRC0079 ALRO 400 D
ALRO 400 D
Generic disc of metal
125x135x11.5 mm
Front Scales: S T R N2 N ( N N2 N3 LL3 LL2 LL )


HSRC0082 ALRO 600 E
ALRO 600 E
Electrical disc of metal
125x135x11.5 mm
Front Scales: n2 C ( D n2 LL Dynamo-Motor Volt ? L )


HSRC0083 ALRO 746 Radiotechniek
ALRO 746 Radiotechniek
Log/tech disc of metal
Front Scales: pF uH N2 N ( N N2 Mcs metrs )


ALRO-PRINT Spoorweglawaai (Train Noise) Reckenschijf 922130

ISRM 13.01.26.02
ALRO-PRINT Spoorweglawaai (Train Noise) Reckenschijf 922130
Made by ALRO-PRINT, Den Haag, the Netherlands - Technical disc of plastic
134x159 mm
Front Scales: Equivalent Geluid Niveau (dB(A), Snelheid Reizigerstreinen (Km/uur) ( Afstand: Zonder Scherm, Met Scherm 1.5m, Sommeren (dB(A) ) Donated and described by David Rance, the Netherlands
\ Note on use: "Spoorweglawaai" translated from Dutch, means railway track noise. Basically it can be used to predict the level of train noise that can be expected under certain conditions. The factors are: (i) the average number of passing electric passenger train bogies per hour, (ii) the average number of passing goods train axels per hour and (iii) the average speed in km per hour of the passenger trains (n.b. for goods trains the pre-set gauge point of an average 75 km per hour must be used). Then for a range of distances (20-250m ) from the track (with or without a 1.5 m high noise barrier), the expected noise level in dB(A) at a height of 5 m off the ground can be calculated. The last "sommeren" or summation scale is used to get a total db(A) noise level reading for the passenger and goods trains combined.


HSRC0029 ALRO Ami-Ro and Imi-Ro-meter
ALRO Ami-Ro and Imi-Ro-meter
Medical slide chart of plastic
184x78x2.2 mm


HSRC0028 ALRO Ami-Ro-meter
ALRO Ami-Ro-meter
Medical slide chart of plastic
184x78x2.2 mm


HSRC0429 ALRO Artillery ST 9 - 430/2 Slide Rule Set
ALRO Artillery ST 9 - 430/2 Slide Rule Set
Military rule/cursor no slide of plastic
314x61x2 mm
Front Scales: 1)
Back Scales: 2)


HSRC0031 ALRO Beton Concrete Calculator

ALRO Beton Concrete Calculator
Concrete disc of metal
122x5 mm


HSRC3519 ALRO Bureau Model Spring load

ALRO Bureau Model Spring load
Log/tech disc of plastic/metal
190x20 mm


HSRC0088 ALRO 04 - 2220 Radio Large PTT

ALRO 04 - 2220 Radio Large PTT
Log/tech disc of plastic
118x3.2 mm (1972)
Front Scales: C and L N2 N ( N khz )
Back Scales: nulniveauspanning C ( Decibel )


HSRC0033 ALRO Carborundum
ALRO Carborundum
Technical disc of plastic
120x185 mm


HSRC0035 ALRO Philips Cobol Analyser
ALRO Philips Cobol Analyser
Technical disc of plastic
190x3 mm
Front Scales: Many scales
Back Scales: Many scales


HSRC5731 ALRO Commercial System Ha Tex
ALRO Commercial System Ha Tex
Log/finan disc of metal
125x135x12 mm
Front Scales: C ( D Pound )


HSRC0036 ALRO Phillips Data Systems Computer
Disc P 300 Series
ALRO Phillips Data Systems Computer Disc P 300 Series
Other disc of plastic
245x2.2 mm


HSRC0050 ALRO De Muiderkring, Bussem, Nederland
ALRO De Muiderkring, Bussem, Nederland
Log/tech disc of plastic
60x4 mm
Front Scales: 1 2 N2 N ( N 3 4 )
Back Scales: V1 V2 W1 W2 5


HSRC5785 ALRO De Muiderkring Large
ALRO De Muiderkring Large
Generic disc of metal


HSRC0043 ALRO Den Haag, Aangeboden Door De Fabrikant
ALRO Den Haag, Aangeboden Door De Fabrikant
60x4 mm
Front Scales: N2 N ( N )
Back Scales: N N3 tg sin


HSRC0058 ALRO Early Disc,
with Ir. C.J. Dussel & A. Pasveer logo
ALRO Early Disc, with Ir. C.J. Dussel & A. Pasveer logo
Generic disc of metal
125x135x12.4 mm
Front Scales: C ( D )


HSRC0059 ALRO disc
ALRO disc
Generic disc of metal
120 mm
Front Scales: C ( D )


HSRC2774 ALRO ELA Philips ELA 68/43/4112
ALRO ELA Philips ELA 68/43/4112
Log/tech slide chart of cardboard/plastic
283x83x1 mm


HSRC0038 ALRO Geluidsniveauverschil Van Gevels
ALRO Geluidsniveauverschil Van Gevels
134x159 mm (1981)


HSRC0041 ALRO gti installatietechniek
ALRO gti installatietechniek
Technical slide chart of plastic
74x150x1.5 mm


HSRC0042 ALRO T.K.F. Haaksbergen
ALRO T.K.F. Haaksbergen
Generic disc of plastic
60x4 mm
Front Scales: N2 N ( N )
Back Scales: N N3 TG SIN


HSRC3406 ALRO Holland Ericsson
ALRO Holland Ericsson
Generic disc of plastic
60x4 mm
Front Scales: N2 N ( N )
Back Scales: N N3 tg sin


HSRC0046 ALRO Kipp Delft Holland
CYCLOOP Diaferometer
ALRO Kipp Delft Holland CYCLOOP Diaferometer
Log/tech disc of metal
98x5 mm
Front Scales: C ( D )
Back Scales: 1 ( 2 )


HSRC0047 ALRO KLM Gasoline and Oil conversion factors
ALRO KLM Gasoline and Oil conversion factors
Conversion disc of metal
142x8 mm


HSRC0032 ALRO Laboratorium Voor Bloembollen
onderzoek Lisse
ALRO Laboratorium Voor Bloembollen onderzoek Lisse
Other disc of plastic
120x120x1 mm


HSRC0048 ALRO Lettergieterij
ALRO Lettergieterij
Generic disc of plastic
60x4 mm
Front Scales: C ( D )
Back Scales: 1) 2) 3) 4)


HSRC3520 ALRO Lettergieterij Amsterdam
ALRO Lettergieterij Amsterdam
Generic disc of plastic
60x4 mm


HSRC0034 ALRO disc with CJD logo
ALRO disc with CJD logo
Generic disc of metal


HSRC0039 ALRO Medisch Geneesmiddelen Interactie.
ALRO Medisch Geneesmiddelen Interactie.
Medical disc of plastic
140x1.8 mm


HSRC0049 ALRO Militaire Rekenschijf (Military) disc
ALRO Militaire Rekenschijf (Military) disc
Military disc of metal
132x8.5 mm
Front Scales: tg sin-tg sin C1 0/00 1 C ( D 2 A )


HSRC0030 ALRO Philips Audio Communications
ALRO Philips Audio Communications
Log/tech slide chart of plastic
184x78x2 mm


HSRC0045 ALRO Philips Calender disc
ALRO Philips Calender disc
Calender disc of metal
120x4 mm (1935)
Front Scales: 1 ( 2 )


HSRC3080 ALRO Philips CJD
ALRO Philips CJD
Electrical disc of metal
125x135x12 mm
Front Scales: uH uuF C ( D N1 N2 Frequency Wavelength )
Back Scales: In lid: 8) 9) 10)



HSRC0037 ALRO Philips ELA Audio Communications
ALRO Philips ELA Audio Communications
Log/tech slide chart of plastic
184x78x2 mm


HSRC0056 ALRO Philips Telecommunication
ALRO Philips Telecommunication
Log/tech disc of plastic
60x4 mm
Front Scales: pF uH N2 N C ( D N Frequency Wavelength)
Back Scales: 5) 6) = 7) 8)


HSRC0054 ALRO Prototype
ALRO Prototype
294x36x6 mm
Front Scales: 27cm // K A [ B CI C ] D L
Back Scales: [ S S&T T ]
HSRC


HSRC3411 ALRO Radio 04 - 2220 Small PTT
ALRO Radio 04 - 2220 Small PTT
Log/tech disc of plastic
80x6 mm
Front Scales: C L N N ( N n l )
Back Scales: 1 C ( Decibel )


HSRC0055 ALRO Shell Viscoklok 1962
ALRO Shell Viscoklok 1962
Log/tech disc of plastic
185x3 mm (1962)
Front Scales: 1 ( 2, 3, 4, 5 )


HSRC0027 ALRO Tires
ALRO Tires
Technical disc of metal
120x135x12 mm
Front Scales: 1 2 3 4 ( 5 6 7 8 9 )


HSRC0040 ALRO type Go.A
ALRO type Go.A
Generic disc of metal
125x12 mm
Front Scales: 1, 2, 3, 4 ( 5, 6, 7, 8 )


HSRC3425 ALRO Vaste en Beweegbare Bruggen
ALRO Vaste en Beweegbare Bruggen
Technical disc of bakelite/plastic
135x6.5 mm
Front Scales: Many scales, Back Scales: Many scales


HSRC0057 ALRO Vondelingenplaat
ALRO Vondelingenplaat
Other disc of metal
125x9 mm
Front Scales: % ( Kg gram )


HSRC0063 ALRO WeR2 and 4, O.K. Electroden
ALRO WeR2 and 4, O.K. Electroden
Generic disc of metal
125x135x12.4 mm
Front Scales: A C ( D B Rec N3 log )


HSRC2697 ALRO WeR2 and 5
ALRO WeR2 and 5
Generic disc of metal
120x130x12 mm
Front Scales: N2 N ( N2 Rec N3 log )

ALRO Timeline and History

The birth of ALRO began in the 193's with the development of the foldable calculator by C.J. Dussel and W. Pasveer. The history of the company can be summarized in the following timeline.

1913 - French patent (No. 461479) of P.-J. Denis for a calculator, to which reference is made in Dussel's patent application.
1930 - U.S. patent (No. 1,780,078) of M.P. Hite for a calculator, which is also referenced in Dussel's patent application.
1931-1934 - Founding of Ir. C.J. Dussel & W. Pasveer, Wild Hoeflaan 21, The Hague.
1931-1935 - Development by Dussel and Pasveer of ALRO calculator.
1935-1936 - Application by Dussel and Pasveer of patent for shaft and disc construction of the circular calculator in six countries.
1935-1937 - Production ALRO first disc calculators.
1935 - Death of W. Pasveer.
1936-1938 - Grant of Patent:.
England (No. 443689/36, 28.05.1936).
Belgium (No. 413897).
France (No. 808,295, 2/2/1937).
Germany (No 643 571, 04.12.1937).
Netherlands (No. 41324, 16.08.1937).
USA (No. 2117155, 10.05.1938, and to Dussel Jelier).
1938, August 26 - Formation by C. J. Dussel and C.A. Jelier of the firm ALRO Society for the Exploitation of Patents NV, The Hague (29/09/1938 Dutch Government Gazette, No. 188).
1938-1960 - Production ALRO disc calculators including all patent numbers.
1940 - C.J. Dussel resigns as director, but remains involved in the design ALRO.
1942 - J. Ruyter is the director of the company ALRO.
1945-1960 - Development of most types of 13 cm calculator.
1949 - Swiss patent (No. 265,561) granted to ALRO for the scale design of the calculator type 1010 "Commercial".
1959 - ALRO decides to focus on plastic cards.
1987 - October 30 ALRO is sold to Deltacom Group BV Rotterdam via an equity transaction, but remains provisionally N.V. exist.
1988 - ALRO ends up in the English firm Delarue.


ALRO Brochure showing available models in 1950.


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