Marchant calculator

 The Marchant Calculating Machine Co. was founded in 1911 by Rodney and Alfred Marchant in Oakland, California.

The company built mechanical, and then electromechanical calculators which had a reputation for reliability. First models were similar to the Odhner arithmometer.

The first Marchant calculators differed greatly from their later Silent Speed Proportional Gears machines, which were by far the fastest of their type, running at 1,300 cycles per minute. These machines are of considerable technical interest, and are far better known than the earliest ones. Their mechanical design was very unusual in that their result dials (sums, differences, and products) moved at speeds proportional to the digit in the corresponding column of the keyboard. A '1' in the keyboard caused its dial to move the slowest, while a '9', the fastest. Probably the only other such machine was the European Mercedes Euklid, which had a very different (and apparently much simpler) design.

Silent Speed 8D

Carrying to the next higher order was done (effectively) by a 10:1 gear ratio, rather like traditional watthour-meter dials. This was probably unique in a calculator. While running consecutive 'add' cycles to develop a product in multiplication, much of the mechanism was running at constant speeds. All other mechanical calculators had result dials that moved only at one speed, but for different amounts of time, naturally for longer times when larger digits were to be entered. They started quickly, ran at one speed, and stopped quickly. (They also had mechanisms to prevent overshoot (known as coasting) when they stopped.)

Figurematic (1950-52)

In the Marchant, each column had its own mechanism that might be described as a nine-speed pre-selector transmission. Once engaged, that was what made the dials move at speeds proportional to the digit in that column. This meant that the machine contained, in all, several hundred individual gears.

Carries from lower-order digits came in via one planetary differential per dial. If one held down the + bar, in neighboring columns to the left (with zeros for them in the keyboard), one could see two or maybe three higher-order dials moving at the speeds one would expect.

Watthour meter dials, like the hour hand of a clock, make no attempt to point to the correct digit, if the dial to the right is between, for example, 3 and 7, or so. Such misalignment would be intolerable in a calculator's dials, so each of the Marchant's dials had a constant-lead ("snail") cam attached. Omitting important details, this cam determined the amount of movement needed to realign the result dials. That correction was applied by a second spur-gear differential, again, one per dial.

Some calculators that had been serviced had dials that were mispositioned by (probably) 3.6 degrees; the gears weren't quite meshed correctly when reassembled.

1960s SCM Marchant calculator

The calculator was very complicated compared to, for example the Friden STW, a machine notable for its relative internal simplicity. Much of the Marchant's control mechanism was beneath the keys, and had about 25 "layers" of levers, linkages, latches, and such. It had three driveshafts, extending across the mechanism. Most other calculators had only one.

                                                                                                                                                                                                                           source:wikipedia.org

second analytical engine

 Second analytical engine was designed by Percy Edwin Ludgate (2 August 1883 – 16 October 1922) was an Irish amateur scientist.

Working alone, Ludgate designed an analytical engine while unaware of Babbage's designs, although he later went on to write about Babbage's machine. 

Ludgate's engine used multiplication as its base mechanism (unlike Babbage's which used addition). It incorporated the first multiplier-accumulator (MAC), and was the first to exploit a MAC to perform division (using multiplication seeded by reciprocal, via the convergent series (1 + x)⁻¹). 

Ludgate's engine used a mechanism similar to slide rules, but employed his unique discrete Logarithmic Indexes (now known as Irish logarithms (Boys, 1909)), and provided a very novel memory using concentric cylinders, storing numbers as displacements of rods in shuttles. His design featured several other novel features, including for program control (e.g. preemption and subroutines – or microcode, depending on viewpoint). The design is so different from Babbage's as to be a second type of analytical engine, preceding the third (electromechanical) and fourth (electronic) types. The engine's precise mechanism is unknown as the only written accounts of the engine which survive do not detail its workings, although he stated in 1914 that "[c]omplete descriptive drawings of the machine exist, as well as a description in manuscript" – these have never been found.

He was one of a few independent workers in the field of science and mathematics. His inventions were worked on outside a lab. He worked on the inventions only part-time, often until the early hours of the morning. Many publications refer to him as an accountant, but that came eight years after his 1909 analytical engine paper. Little is known about his personal life, as his only records are his scientific writings. The best source of information about Ludgate and his significance lie in the work of Professor Brian Randell. As from 2016, a further investigation is underway at Trinity College, Dublin under the auspices of The John Gabriel Byrne Computer Science Collection.

ball-and-disk integrator

 The ball-and-disk integrator is a key component of many advanced mechanical computers. 

Through simple mechanical means, it performs continual integration of the value of an input. Typical uses were the measurement of area or volume of material in industrial settings, range-keeping systems on ships, and tachometric bombsights. 

The addition of the torque amplifier by Vannevar Bush led to the differential analysers of the 1930s and 1940s

The basic mechanism consists of two inputs and one output. 

The first input is a spinning disk, generally electrically driven, and using some sort of governor to ensure that it turns at a fixed rate. The second input is a movable carriage that holds a bearing against the input disk, along its radius. 

The bearing transfers motion from the disk to an output shaft. The axis of the output shaft is oriented parallel to the rails of the carriage. 

As the carriage slides, the bearing remains in contact with both the disk & the output, allowing one to drive the other.

The spin rate of the output shaft is governed by the displacement of the carriage; this is the "integration." When the bearing is positioned at the center of the disk, no net motion is imparted; the output shaft remains stationary. As the carriage moves the bearing away from the center and towards the edge of the disk, the bearing, and thus the output shaft, begins to rotate faster and faster. Effectively, this a system of two gears with a continuously variable gear ratio; when the bearing is nearer to the center of the disk, the ratio is low (or zero), and when the bearing is nearer to the edge, it is high.^[1]

The output shaft can rotate either "forward" or "backward," depending on the direction of the bearing's displacement; this is a useful property for an integrator.

Consider an example system that measures the total amount of water flowing through a sluice: A float is attached to the input carriage so the bearing moves up and down with the level of the water. As the water level rises, the bearing is pushed farther from the center of the input disk, increasing the output's rotation rate. By counting the total number of turns of the output shaft (for example, with an odometer-type device), and multiplying by the cross-sectional area of the sluice, the total amount of water flowing past the meter can be determined..

Elephant clock

 

Ismail al-Jazari:-

A Muslim polymath from  Jazira in Mesopotamia. He was a scholar,engineer,artist,mathe,mathematician etc.He is best known for writing The Book of Knowledge of Ingenious Mechanical Devices. In this book, he has written or given many tricks related to  engineering.

In this book in 1206, where he described 100 mechanical devices, some 80 of which are trick vessels of various kinds, along with instructions on how to construct them. He is credited with the inventions of the flush toilet and the elephant clock.

We are going to discuss about elephant clock.

1.It consisted a weight powered water clock in the form of an Asian elephant. The various elements of the clock are in the housing (howdah) on top of the elephant.

2.The timing mechanism is based on a water-filled basin hidden inside the elephant.

3.In the bucket is a deep bowl floating in the water, but with a small hole in the centre. 

4.The bowl takes half an hour to fill through this hole. In the process of sinking, the bowl pulls a string attached to a see-saw mechanism in the tower on top of the elephant. This releases a ball that drops into the mouth of a serpent, causing the serpent to tip forward, which pulls the sunken bowl out of the water via strings.

5. At the same time, a system of strings causes a figure in the tower to raise either the left or right hand and the mahout (elephant driver at the front) to hit a drum. This indicates a half or full hour. 

6.Next, the snake tips back. The cycle then repeats, as long as balls remain in the upper reservoir to power the emptying of the bow.

                                                                                                content source:wikipedia.org

Su-song

A chinese polymathic scientist, excellent in various subjects like mathemetics,astronomy,cartography,geogrphy,horology,pharmacology,mineralogy,metallurgy,zoology,botany,mechanical engineering,hydraulic engineering,civil engineering,architecture,invention,art,poetry,philosphy,antiquities. and stateman during Song dynasty. He made clock tower. 

In this tower, 

1. we can see specific building with turret clock and have one or more clock faces.

 2.Many other clock towers are freestanding structures but they can also adjoin or located on the top of another building.other building have clock faces but they have some other functions. 

3.clock owers are common sight in many parts with some iconic buildings. 

4.The mechanism inside the tower is known as a turret clock. 

It often marks the hour (and sometimes segments of an hour) by sounding large bells or chimes, sometimes playing simple musical phrases or tunes. Some clock towers were previously built as Bell towers and then had clocks added to them. As these structures fulfil the definition of a tower they can be considered to be clock towers.

history of computer in Nepal

 We have been using computer since many years.In Nepal, if we look, it was started from 2028 B.S. This was the starting stage  of computer in Nepal. The government of Nepal had to count population of 2028 B.S. For this ,the government brought IBM 1401 series computer on lease i.e. Rs 125000 per month.This computer was helpful and completed the census in 1 year 7 months and 15 days.

                                                                                      Later on, for next census of 2038 B.S., another computer named ICL 2950 was brought. It was too much expensive to bring this so the government could not afford and it was funded by UNDP and UNFA at 2 million US dollar. Then 2039 B.S onwards many micro computers (Apple,sirius,vector etc) were brought in Nepal.

                         During that period we had no man-power to use to operate computers. For this many trainers were imported ;especially from UK;and given tariinig to Nepalese people.Nepal gover,nment set up an EDP (Electronic Data Processing) as training center.Later it was renamed to NCC(National Computer Center). 

                               Now-a-days, we have many training institutes across the Nepal. They are providing computer education as well as training to students.

                                                                   Not only that much,Nepal governement 's initiation is also praise-worthy in the field of IT.

Antikythera mechanical computer

 It is an acient Greek computer ,believed as first analog computer powered by Orrey. 

It was used to predict astronomical psoition and calendar in advance.

As the history says it was retrieved from the sea from a seawreck.

It was believed that it was invented by Greek scientist in 87 B.C.

Features:-

1. It contains two faces front and rear face.

   Front face:-

          ->The front face has two concentric scales.

          ->The first scale marks the Greek sign of the Zodiac.

         ->The outer scale which is moveable ring that fits the flush with the surface and runs in a channel, marked off with what appear to be days.

        ->The outer layer has been presumed to represent 365 days;however, recent reseearch shows soe evidence that it is mostly likely to divide into 354 intervals.

         ->If onesubscribes to the 354 days evidence, then most likely the interpretation is that ring is a manifestation of a 354 day lunar calendar.

      

photo credit:wikipedia.org

        ->The lunar calendar purpose was t serve daya to day indicator of successive lunations and have assisted with the interpretation of lunar  phase pointer and metonic and saros dials. 

   Rear face:

          ->This face contains five dials: two large displays the Metonic and Saros and three small indicators,called Olympiad dial.

          ->the metonic dial is the main upper dial on the rear of the mechanism. the metonic cycle defined in Physics is very closed to 19 tropical years. I

          ->It is therefore a convenient interval over which to convert between lunar and solar calendars.

        ->The metonic dial covers 235 months in five rotations of the dial.the pointer points to the synodic month,counted from new moon to new moon.