Sources: They do conflict, so welcome to the fun!

Modern:

Old Spanish Measures:

    The Spanish system of measures contained the following units - there were many more than those we list here.  The official Spanish vara de Burgos (or vara de Castilla) was set by royal Spanish edict in 1801 and measured 0.8359 meters (32.909 inches). 

Mexican California 1840's:

    The official vara had 22 accepted variations in California prior to the Treaty of Guadalupe-Hidalgo of 1847, which set the vara at 33 inches.  New variations upon 33 inches arose in south-west US until 1855 when the Texas vara was set at 33.333 inches.

US California 1850+:

    Deeds and survey maps used the following survey measures, still in use today:

Argentina 1835, pre-metric:

    In 1835, the Argentine system of distance & length measures recognized the following units:

    In Santa Fé, the shorter vara de Bustinza was an accepted alternative to the official measure.

Modern:

Mexican California 1840's:

    Please bear in mind that many survey maps of the early 1800's were estimates made without benefit of proper measurement, e.g. California diseños (survey maps) of the 1840's were often made a ojo (estimated by eye).  The 2.6% maximum variance in the standard Mexican land measure of the 1840's, sitio de ganado mayor, pales in comparison to the huge errors in mapping and translation - witness the legal problems Wilhelm's inaccurate diseño (made a ojo from the back of a horse) caused the subsequent owners of Rancho Herman.

Sitio de Ganado Mayor:  During the first half of the 1800's in Mexico, of which California and Texas were part, large land grants were measured in sitios de ganado mayor (or sitios) - often translated into English as leagues without proper qualification.  Originally one sitio de ganado mayor was the amount of land considered necessary for a cattle ranch, however, land grants most often consisted of several sitios de ganado mayor.  A sitio de ganado mayor was a square of 5,000 x 5,000 varas.  Simple enough, except that the length of the vara varied over time and place - see above.  It was also considerably smaller than the Spanish or Argentine legua (of 6,666.7 or 6,000 varas per side respectively). 

Fanega de Sembradura:  The highly inexact area sown by a fanega of seed - varies by place, year, person, and seed sown: corn (0.6 - 8.8 acres) or wheat (0.15 - 1.8 acres).  The sizes in the above table were used by Governor Vallejo for wheat sown at Fort Ross in 1841.

Argentina 1835, pre-metric:

Cuadra: Crop yields and land prices were often quoted in cuadras until about 1950.  (To further confuse crop yields, it's possible they used the old quintal of approx.  46 kg. and not  the metric quintal of 100 kg.!)

Legua: In  Argentina, the size of estancias (aka: camps or ranches) are often broadly described in leguas de campo or leagues of land.   In modern terms, a legua or league is a metric square league - we include it here for easier comparison.  

Suerte de estancia: An old term not currently in use. 

Modern:

    In the following table we include in green multipliers for converting crop yields between quintales por hectarea and US bushels per acre - the common measures of Argentina and USA.  A quintal is a colloquial term for 100 kilograms, and comes from an older measure now obsolete which weighed about 46 kg. (see below).

Bushel:  In spite of being a volume measure it persists in the US for stating crop yields and prices (though all measuring is done by weighing, the weights are then converted to bushels!).  Being a volume measure, the weight of each seed is dependent on its density (we leave it to the farmers amongst us to adjust for moisture and foreign material).

Mexican California 1840's:

    The following are selected Mexican measures from Rescate de Antiguas Medidas.  We have not discovered a definitive study of Californian measures, and we have some doubts about the accuracy of these conversion factors - their relative values don't appear to be simple multiples of the next smaller unit, as would be expected.

Argentina 1835, pre-metric:

   Estimating the value of money seems to be an art and not an exact  science.

http://www.economics.utoronto.ca/munro5/MONEYLEC.htm

http://www.cyndislist.com/money.htm

    Giving up on all the economic formulae, we decided to compare currency values in terms of US Dollars (close of 31 Dec., 2000) as follows:

Currencies - Valued in US Dollars, Dec. 31, 2000:

Bold - gold standard, Bold - silver standard.

Some Issues with Precious Metals & Currencies

    Gold Standard: It first emerged in the UK during the early 1700's, it was abandoned in 1790 (due to the Napoleonic wars) then resumed in 1819.  Its adoption spread during the 1800's - the US adopted it in 1879 (dropping its bimetal standard with silver).  It effectively placed the world economy on a single currency - the US Dollar was valued at 1.5047 grams (23.22 grains), the British Pound at 7.3224 grams (113.0 grains).  Attractive to entrepreneurs and capital rich countries (UK, US), it harmed the working class and primary product exporting countries (Argentina, Canada), and deepened economic down turns into depressions.  It collapsed with WW-I, was then resurrected for a short while until it was finally laid to rest by the Great Depression.  For more details, see:

http://www.huppi.com/kangaroo/L-gold.htm

http://www.cyberussr.com/hcunn/gold-std.html

    Specie: If a transaction was made using printed currency or bank drafts then converting to US Dollars and adjusting for inflation provides us a reasonable estimate of the value of that transaction in modern terms.  However, if we know the transaction was made in specie (weight of metal - coins and/or bullion) then we might also adjust for changes in the relative value of the metal.  Both gold and silver were relatively much more expensive than they are today.  Silver has especially dropped in value.  Comparing the value of one unit in 1850 converted to USD-2000 vs. the value of the same unit in 2000 - gold ounce: $736.80 vs.  $272.15, silver ounce: $47.39 vs.  $4.60.  After accounting for inflation, an ounce of silver cost ten times as much then as in 2000, gold almost tree times as much.  The ratio of silver ounces per gold ounce remained relatively stable at 15:1 or 16:1 until the mid to late 1870's when it began to slip with the discovery of large silver deposits.  At the close of 2000, the silver : gold ratio was 59:1.

    Buying Power & the Cost of Living: From the Historical Text Archive:

    Economists, when calculating inflation (i.e. the US-Consumer Price Index,  used to determine the current value of USD in the table above), exclude the cost of improvements to the standard of living (horse vs. combustion engine, candles vs. electric-light, abacus vs. computer).  That is, the above table underestimates the relative social importance of a $1 (USD) earned then vs. now (anyone have a better term?).   For example, the activities & skills of a cowboy have changed little (vs. other professions) during the past 100-150 years.  By several accounts, in about 1875 a cowboy earned $30 per month, or $360 per year, which when adjusted for inflation (per the US-CPI) is approx.  $7,800 per year in USD-2000 terms.  In 2003, the mean wage of a farm hand in New Mexico was $20,010 per year.  Comparing these wages for the same approx. work provides a multiplier of approx. 2.5 by which the US-CPI understimates the relative social importance of a dollar earned by a cowboy in 1875 vs. 2000.   However wildly unscientific our Bz-RSI multiplier might be, it provides us a simple means for understanding in today's terms (within the context of US society) the relative social importance of a dollar earned in 1875.  [Example: In 1874 Wilhelm Benitz sold his Oakland real estate for US$105,000, adjusted for inflation per the US-CPI it was worth $2,200,000 USD-2000, adjusted for relative social importance per our Bz-RSI it was equivalent to $5,500,000 USD-2000.]  Caveat: Use with care, other bases of calculation and dates will provide very different multipliers. 

    Buying Power is what a unit of currency will buy in one place (city, country) versus another on a given date.  We won't be analyzing buying power - it is beyond our scope.  Here is an example from the Economist magazine (17 Jan.'04) - it showed how the buying power of the US Dollar varied geographically by converting to US dollars the local price of a McDonald's Big Mac hamburger: Switzerland $5.11, Euro area $3.48, USA $2.80, Argentina $1.43, China $1.23.  Same product, same currency, different price.

    Cost of Living is usually expressed in comparative terms, e.g. New York is twice as expensive to live in as Miami, Buenos Aires twice as expensive as Bahia Blanca.   We won't be analyzing cost of living either - it too is beyond our scope.   However you should be aware that:

        Measuring Precious Metals:  Precious metals have their own (Troy) system of weights and measures.  Here is the conversion table we use.

Avoirdupois: The system of common measures used in the UK and US.

    Grains:  The smallest (basic) unit of measure, which of course varied by country, etc.:

    For more conversion tables, try:

http://www.ccsilver.com/reftable/conversion.html

 http://webserver.lemoyne.edu/faculty/giunta/archemg.html

Brief Histories of the Currrencies:

Spain:  The Spanish Real de a Ocho reigned as the monetary standard in world trade for nearly 400 years, from 1500 until the late 1800's, giving birth to more than 50% of the world's currencies, including the US dollar.  The official name of the Spanish colonial and early Mexican currency was the Real de a Ocho (o Ocho Reales) - "pieces of eight" - which became known colloquially as a Peso, Peso Fuerte, o Peso Duro because of its unchanging weight in silver.  According to a Spanish Royal Ordenanza (decree) of 1497, 67 Reales were to be minted from a single Marco de Castilla of pure silver that weighed 230.465 grams (the standard weight of a Cologne Mark), i.e. each Real weighed 3.4335 grams and each Peso Duro weighed 27.4680 grams.  For more details, see: (target web-site disappeared on me).

Argentina:  Following independence from Spain in 1810, Argentina continued to recognise the Spanish Peso Duro (known colloquially as a Patacon) as legal tender for a number of years.  The Peso Argentino, first emitted in 1812, fared badly during years of chaos until 1853 when order was restored.  In 1881 Argentina struck its first silver Peso, valued at 1:1 with the Peso Duro (Spanish Real de a Ocho).  However, it soon lost value when once again too many bank notes were printed.  During the 1860's and 1870's, Franz and Wilhelm Benitz paid for their land purchases in Pesos Duros.  For more details, see:

http://en.wikipedia.org/wiki/Argentine_Currency_Board

http://en.wikipedia.org/wiki/Historical_exchange_rates_of_Argentine_currency

Mundo Andino.com

http://www.mundoandino.com/Argentina/Historical-exchange-rates-of-Argentine-currency

    Germany:  In very simplified terms, three currencies (there were many others, most local) were the basis of trade during the period that concerns us, 1830-1870: (1) Thaler - used in the northern principalities including Mecklenberg and Prussia; (2) Gulden - used in the southern principalities including Baden; and (3) Mark-Banco - used by Hamburg and Luebeck.  In 1871 the three currencies were consolidated into the Mark.  For more details, see:

http://www.globalfindata.com/frameset.php3?location=/gh/109.html

http://www.germanlife.com/Archives/1997/9712_01.html

Mexico:  During the years we are concerned with, 1830-1850, Mexico continued with the Spanish Real de a Ocho (Peso Fuerte), minting its own - see Spain above.  For more details, see:

http://www.chicagocoinclub.org/projects/PiN/ccp.html

UK:  The British Pound became of interest to the family when they began travelling to Europe in the late 1800's and/or married British subjects or their Anglo-Argentine descendants.  Consequently, we include it here.  In the simplest terms, one pound is 20 shillings or 240 pennies.  In 197x, the pound is decimalized into 100 (new pence) pennies.  For the rest, find a pub, offer a Brit a pint and have him explain farthing, hapenny, pence, crown, guinea, etc.

US:  The US Dollar, the basis of our tables of comparison, has had its tribulations like any other currency.  Named after the German Thaler, its value was originally based upon the Spanish Real.