There are many books in Sanskrit devoted to science and technology such as Yantra Sarvaswa, Samar¡ngana S£tradh¡ra, Tantra Prad®pica, Pr¡ch®na-S¡dhana, Silptantra Rahasya, Yukti Kalpataru etc.

Several other books pertaining to other sciences also contain technical sections such as Artha S¡stra, Rasa S¡stra, Ganita S¡stra, D¡rutantra, V¡stu Tantra, Sthapatya S¡stra etc.

We shall see the development of these technologies one by one.

These are very primitive technical developments of man. A potter is supposed to be the first engineer indeed ! His wheel may be considered as the first machine in the world as its principle is still used for our main machine tool- The Lathe. In the Vedas the potter (Kul¡la) is mentioned and even the Creator is compared with him. They also mention about the burnt pots and other forms of clay materials. Much can be learnt from the Indus Valley studies. Generally the pots were made of black or red clay and then they were burnt in special kilns whose shapes were generally cylindrical, pear-shaped or round. They were lined with bricks made of mica, sand and lime-stones. Even the pots were glazed and painted in an attractive fashion. For giving different shades to the pots they used several chemicals such as Copper Oxide for blue shades, Iron Oxide for bluish-green shades, Manganese for dark maroon shades etc. This is confirmed by the recent Dw¡raka excavations.

Temporary controlling was done for glazing and the chemicals used were 25.2% FeO, 46.55% SiO₂, 15.53% Al₂O₃, 4.74% CaCO₃, and 3.43% Magnesia. The most complicated and geometrical shapes of the pots throw light on the Harappan skill and the process's technical soundness. Some of the pot sections can be studied from the Figures (i) to (vii) (Plate I).

The seals made of terra-cotta very well depict the craftsmanship and glazing skill of the Indus people. The marvelous shapes engraved in the clay pieces are the best proofs.

The blending of clay with other ingredients and making a compact paste like slurry were all made according to the pre-determined standards.

Indus civilization is also famous for its burnt bricks. The bricks were made of clay, silica, lime stone and others, the dimensions of which are given in the K¡syapa Samhita (11.72" x 5.25"x 7.5"; 11.55" x 7.75"; 10.5" x 5.5" x 7.5"). This steadiness in dimensions shows their high level of Civil Engineering skill. Invariably wooden moulds were used to make these bricks and then they were burnt in special kilns. Before the Egyptian civilization, Indians had acquired a high degree of mastery over ceramics, pottery and brick making.

In the Atharvan period, the technique was highly improved including preparations of alloys. Mining and other techniques were also known to the Vedic people.

In Îgveda it is often described that Indra destroyed the Ayasepur¡s (metallic towns) of Dasyus.

Herodotus (500 BC) mentions about the high quality of Indian iron. Quintus Curtis says about the purity of gold and steel alloys given by Pourava to Alexander. Pliny refers to the fine quality of steel products in India. Even the Romans imported steel from India for its high quality and they were using this steel for their armours and other military equipments.

The abundant usage of Iron is confirmed by the archaeological excavations at Delhi, Roopar, Nasik, Madhya Pradesh, Rajasthan, Taxila, Orissa and other places, where iron pillars, arrows, nails, hooks, bars, spikes, daggers, bowls, tongs, chisels, anvils, hoes, adzes and several others were found in large numbers.

Metal casting - considered to be the oldest of all production techniques - evolved considerably in ancient India. From early Vedic time we can trace its development. In Îgveda some equipments used for casting - Dhamatri (Cupola), Bhastri (Blower), Titau (Seives), Sh£rpa (Trays), Gharma Ayanmaya (Crucible) etc., - are mentioned. In Îgvedic period Copper, Bronze, Gold, Silver and later Iron were used along with other metals for casting purposes. The axes, ploughs, and other domestic implements and many sacrificial equipments were made of cast metals (Fig II). The áyreperdyu method along with some other methods was extensively used for casting. This was called Madh£cciÀta Vidh¡na (investing casting). Here model or pattern was made of bee wax and S¡la VrkÀa Rasa. Then the moulding sand (a fine blend of clay, sand, charcoal, husk, cowdung, gingillee oil, salt and others) was pasted on it. After drying, by external heating of the mould, the wax inside was melted and taken out through a hole and pouring basin already made in the mould. Then the actual molten metal to be cast is poured in the mould cavity. Even now, this method is used for making our finest art pieces in metal without any change (See Fig III). This method, with some minor changes is still universally used in our casting industries. This investment casting method is the most ideal one for getting intricate, preferably dimensioned, complex, highly smooth and defectless castings.

In the Harappan civilization, we also notice their proficiency in core making and casting, using different core boxes. First, the cores were made out of a special type of foundry sand which involved clay, sand, charcoal, gingillee oil, cowdung, s¡la-vrkÀa rasa etc., and several needles were pierced inside with some portion of them projecting outwards. On this core, the required form was coated and shaped. Then the moulding sand was pasted on it with all the gatting systems provided. After this, as usual, the mould was dried; the wax was removed and thus the system will be made ready for pouring (See Fig IV).

Open cast or mould, closed mould, double moulds were some other techniques of moulding. Generally wooden and clay patterns were used, but iron or steel patterns were also in use.

Figs. V & VI illustrate ancient furnaces. Their construction and working principles are still conversant with the modern furnaces. Especially, the second furnace resembles our Cupola in many ways. The capacity of the first furnace is about 100 lbs. metal or ore, 240 lbs, with charcoal and some amount of lime as flux. The capacity of the second furnace is much more than the previous one.

According to the norms laid down by Viswa Karma, Maya, Viswarupa etc., the idols were cast and carved. Accordingly, every sculpture should be perfect in t¡lmana, mudra, bhangi, bh¡va and other details. Thus perfection was the aim. The results of this skill are the wonderful Natar¡jas, K¡l®ya Mardanas, Nymphs, Lamps, doors & frames, carts and cars and still many others.

One of the best evidence for the metal casting and forging skill is the wrought iron pillar at Delhi, near Qutub Minar (4th century A.D). Its height is 24'3", with 1' 8" ground, 16.4" to 12.05" from base to apex. Sp.gr. of this is 7.5 and the total weight is 6 tonnes. The composition is - Iron 99.72%, Carbon 0.08%, Silicon 0.046%, Sulphur 0.006%, Phosphorus 0.114%, Nitrogen 0.32%, Copper 0.034% and Manganese nil. The pillar is free from rusting and corrosion to this day. High phosphorus and low sulphur percentage may be the reason for its non-rusting quality. But the technique is still unknown !

Especially at the time of Mughals many military equipments were made of casting. The Malik-I-Maidan, Bulan-Darwaza cannon are some striking examples. Undoubtedly, our ancient metal casting technology was very high and it is beyond the limit of this article to go into much more details ( Ref . Figs. VII & VIII).

Indians were well versed in material science and metal working since Îg Veda. The fundamental five element concept (Pancabh£ta) and the Vai¿eÀika theory (very close to the atomic theory) of Kan¡da laid a strong basis for developments in this field. The suddha and panc®krta forms of pancabh£tas were also helpful. Gurutva (gravity), Dravatva (fluidity), Snigdhatva (viscosity), Sthitisth¡pakatva (elasticity), Samyoga - Viyoga (Conjunction and disjunction), UtkÀepa, AdhahkÀepa, Ëkuncana, Pras¡rana, Bhrama¸a, Gamana, Sthay®, Ëvartana (these are the various modes of movements in the micro and macro states); Plu¶aka¶va(Springing capacity), Vakr®bh¡vanam (Refraction or bending), Vir£pam (deformation), Draghanam (tension), Pr°·anam (compression) and many other technical terms throw light on the knowledge of material behaviour. They knew rusting and corrosion and also its prevention.

They had skill in metal working. Forging was the earliest technology. Loha K¡ra or the Karma K¡ra was their blacksmith. Ëyohata was the term used for forging. The divine blacksmith (TwÀta) was recognised as a God and he had a share in the sacrifices and this invariably indicates the importance given for this work. Many of the agricultural and military equipments were made by forging. In the Atharva Vedic period forging and other engineering techniques were well advanced. Anvil, tongs, hammer and all the other equipments were made of metal. As usual, temperature recrystallization was practised. Cold working and work hardening were also in practice. This is now confirmed by the metallographic examinations of the samples found in Harappa. Plastic deformation, annealing, grain growth, twinning of grains were seen in Indus metal pieces. Vatsyayana in his K¡mas£tra includes metal working in the list of sixty-four arts. In the later days forging evolved and competed with casting in practice and use ( Ref. Fig. IX).

The other forms of metal working such as drilling, drawing, polishing etc., were also in extensive use. In Îgvedic time the skilled gold working exhibited all the minute techniques of drawing, drilling, etching, polishing etc. The splendid Indian clothes made of pure silver and gold threads were very famous abroad with their names Swarna-á¡t® or Swarnapateh or K¡ncana Vastra. The various forms of gold coins such as Hiranya-NiÀka, Hiranya pinda, Suvarna, áatam¡na, Pada etc., show their skill in coining and gold working. Especially the coins of A¿oka, Samudra Gupta, Harsha and of Vijayanagar Kings show the remarkable skills of Indians in coin technique ( Ref. Fig. XI).

Boring and reaming were also common. Most of the long necked tall vessels were made by spinning knives, arrow heads, razors and others were chiseled out from metal sheets of different thickness. By "sinking", deep pots and pans were obtained. By "raising" techniques, cups and basins were made. Lapping and wire drawing were exactly similar to the modern methods. Metals etching by using sharp tools and acid-wax process was very common. Even now in many parts of India especially in South India, Orissa, and in Rajasthan, fascinating artistic pieces are produced by the above-mentioned old methods in brass, bronze, copper, silver and gold. The most intricate, minute and attractive filigree work in gold and silver is still prevailing.

In the Atharva Vedic period, this mechanism gradually increased.

Engineering drawing was also indicated in Jy¡miti or Rajjuga¸ita. Even the orthographic projection technique was known to Indians and many of the paintings evolved from the native styles confirm this. Later researches in mathematics was not only for the advancement of Astronomy and Astrology but for the development of applied science also. 500 Years before Newton, Bhaskara-II put fourth the fundamental steps in calculus and many Kerala works such as Tantra Sangraha, Karana paddhati, Sadratna m¡la, Yukti Bh¡À¡ and others developed this subject and applied in several ways. These include the design of beams columns, studs, shafts etc. Their technical tensile shear, torsional and compressional strengths were calculated so as to see that they will be within the safer limits when loaded or used. The practical proofs for these are the immovable metallic beams and columns, used in the construction of buildings and Temples at many places in ancient India. One such example is the Gunduchiburi temple at Puri which contains 239 iron beams designed with all engineering techiniques each one having a length of 17' and C/Ss varying from 6 "x 4" to 5" x 6". The 29 iron beams of Konark temple having length 18' to 35' are also remarkable.

By various ancient Buddhist scriptures it is known that the Indian carpentry was one of the highly evolved workshop practices. Pallanka or paryanka (Cot), Ësandi (Chair), Ësandaka (easy chair), Koccaham (Cane Chair) etc., are some examples.

For selecting the proper wood they had a good knowledge of Timber technology also.

i.e . a tree's trunk which possesses less than 50 annular rings is undesirable for wood works. Vi¿vakarma Samhita gives best preservative for wood, iron and even for stones also. The composition for modern cement is also given in it. 'Silpa Tantra Rahasya' deals with fluid mechanics and hydrostatics. This is a Kannada work. A telugu work Pracena S¡dhanamu deals with structures and industrial buildings. It is notable that in Sukran®ti S¡rah (about 400 BC) the method of gunpowder manufacturing is given.

Five units of salt-petre, one unit of sulphur, one unit of charcoal made from arka plant prepared so that the smoke does not escape; all these taken, cleansed with water, powdered and mixed together and squeezed with the juices of arka, mandagalli and garlic ; and dried in the sun, then ground like sugar, it becomes gun powder.

Without cannons and other blasting equipments preparations of gun powder is meaningless. Thus, the names áataghn¢, Sahasraghn¢, Agnivar¿aka and others appearing in Koutil®y¡rtha¿astra and in many other texts make it evident that the manufacturing of these sophisticated equipments involved high technology and precision.

Now we shall look at the mechanical contrivances which used the links and pulleys in a sophisticated way for several purposes. Many of these are mentioned in the ancient texts. The major works include Artha¿astra, Samar¡ngana S£tradh¡ra, Vi¿warupa Samhita, Yantra Tantra Pradepika etc.

Koutilya describes about the construction of Kings' palace in detail and states that some mechanism is to be provided by virtue of which the whole palace should fall within seconds when operated in severe conditions. For this a highly evolved mechanism is essential. The various mechanical devices such as Vi¿w¡sa Gh¡ti, Bhoomukha (crane), Agnivar¿aka, Parjanyaka and others used in wars needed wonderful technical aid. Samar¡ngana S£tradh¡ra mentions all these in detail and it also presents the classification of machines into two (i) Swayamv¡haka (automatic) and (ii) áakrpr®nya. Here again two types. Antarita or Alakshya (hidden), Vykta or Lakshya (open). There are still other divisions according to the five fundamental elemental concept i.e., P¡rthiva, Taijasa, Jal®ya, V¡yavya etc. The definition of machine is given as Y¡m Tr¡yat® Yantram i.e., a machine is one which ( by our controlling ) protects us.

The 20 qualities (gunas) desired in a machine given by Bhoja in the same bok are still valuable and are essential in modern machines also. They include the most basic and technical qualities such as vibration control, smooth working, non-friction, noiselessness, easy operation, good finish, easy start, durability etc.

In pure literature also several tit-bits are seen as the Tantran®la Kuvalaya (mechanised blue elephant for deceiving king Udyana) in Bhasa's Pratig¸y¡ N¡tika and the Jalayantra putrik¡ (a fountain) working similar to the modern ones on the principle of suction and vacuum pumping in the same play (II act). The D¡ruvarma Nirm¡ta Yantra t°ra¸a (a mechanised automatic beam structure designed by D¡ruvarma - The technician) in Visakadatta's Mudr¡ R¡kÀasa N¡takam; the aerial device by which King Sriharsha used to travel as seen in Harsha Carita of Bana Bhatta etc.

Somadeva's Kath¡sarits¡gara, a Sanskrit version of Gunadhya's B¤hatkath¡ in Paisaci gives some information about automatic machines. Accordingly, some dolls - after switching them properly, due to the internal joints framed mechanically - were bringing water, garlands, food etc., and were even talking (K.S.S., Madanmanchuka lambaka Taranga III - 18,19,20). Again in the same taranga, verses 43 to 48 deal with the machines constructed on the basis of Panchabh£tas. In Ratnaprabha lambaka, third taranga's 38-44 verses explain a V¡yantra (wind machine).

Even we find primitive aeronautical science in ancient India. A noteworthy book - the Vaim¡nika áastra of Bharadw¡ja MaharÀi is an unique work. By its language and style, it is dated back to 5th Century. According to this text, Vi¿wakarma, Ch¡y¡puruÀa, Manu, Maya and several others were experts in this science. Here the controlling of a Vim¡na while flying in critical places, between the clouds are all narrated. There are numerous terminologies pertaining to the various parts in a Vim¡na. Some of them are :

Vi¿wa Kriya Darpa¸a infront of the driver, besides this the Sakty¡karÀa¸a yantra, the PariveÀa yantra in all four sides of the Vim¡na, Vairupya darpana and V¡tarodhaka k®lakas below, Vidyut yantra in the north-east direction etc.

The driver should be conversant with the K¤taka, Antar¡la and Dr¿ya rahasy¡. The material used for the construction of a Vim¡na is an alloy of Soumaka, Soundalika and Mourtwika lohas. The resulting alloy according to the text, will be very light and resistive to aerodynamic friction and other calamities. For processing this alloy the required method is given in Lohakalpa and Samsk¡ra Darpa¸a.

Udgama and Panjar¡ were the two forms of energies responsible for take-off and landing of a Vim¡na. There were various forms of acrobatics such as Dayana (coming down), Uddayana (flying above), Sundh®na (hitting the target with high speed), K¡nda (raising suddenly), Vy¡nda(coming down quickly), K¡rpostika (flying still),Smasrin® mandal¡vartin® (spiral or circling flight). These were used in the common situations. But Udv¡nta, Pr¡nta, Ëpluta, Ëviddha, Pras¤ta, Samutt¡r¸a were used while fighting.

Bharadw¡ja explains many types of Vim¡nas such as áakuna Sundara, Rukma, Tripura, Vair¡jika, Garuda and many others. He also gives the detailed description of different machinery parts and mechanisms viz. Keelaka (Gear Mechanism and other handles of levers), OuÀmaka Yantrika (Drying machine), Vatanala ( air duct ), Jalavarana nala ( cooling water circulating circuit ), Tailap¡tra ( oil tank ), V¡ta-p¡caka-tantre-nala ( air filter or air fuel mixer ), Agnisthana (Engine), Vidyut yantra ( Batteries ), Vata-codana-yantra(Propellers), Disapracodakayantra ( steering wheel type direction changer ), Suryasaktya-Karsanadarpana and Souramani ( Solar mirror and solar cell ), Dhumanirgamanala ( Exhaust outlet ) etc.

Yati Baodhananda, a commentator of these works gives some names of the books which were concerned with the mathematical analysis of Indian aeronautics. They are Darpana Prakarmam, Vim¡na Candrika, Vyomay¡na PrakaÀa, Saktibejam, Loharahasyam, Sakti sutram, Dhumaprakaranam, Valmeki ganitam etc. Even Samarangana Sutradhara, Amsu Bodhini etc., deal in some parts of the texts, the same subject.

The distances like Yojana. Krosa, Dhnus, Angula, Hasta, Rajas etc. and the units like pala, bhara, anu etc., were known to the ancients. The stone-made weights were ranging from 1,2,8/3, 4, 8, 16, 32, 64, 160, 200, 350......1200 gms. had a basic weight of 0.8565 gms. as their gradient. The markings on measuring yards were precise to 0.003 m.!!! The smallest bead's length was 1/34". For alloying, perfect balances were used to maintain standard proportions as desired.

Kautilya also describes the method of calibration of weights and he describes perfect balances and their standard dimension also. The Samarvrtta balance resembles the modern physical balance; Parimani still sophisticated one. The Vyavaharike is the modern simple balance. Bhajine, Antahpura-Bhajine were some other types.

Thus we had various forms of scientific measurements.