The metric system was devised a little over one hundred years ago. Many of the world's scientific men were concerned in constructing it. It was first decided that it should be decimal. Next, it was decided that it should be based upon some linear unit, and that measures of surface, volume and weight should be based upon the linear unit primarily. <Callout type="important" title="Critical Rule">The original meter is intended to be identical with the forty-millionth part of the length of the meridian.</Callout> The units employed in the metric system for the measurement of surfaces are simply the squares upon the meter and upon decimal multiples and subdivisions of the meter. For the measurement of bulk, the cubes upon the meter and its decimal multiples and subdivisions are used. In order to obtain a unit of mass, the scientific men who devised the metric system decided that the mass of a given volume of water at the temperature of the maximum density of that liquid should constitute that unit. Hence, the weight of a cubic centimeter of water at 4° C, weighed in vacuo, was called a gram, and that gram is the unit of weight of the metric system. <Callout type="warning" title="Safety Hazard">Whether the theoretical meter, which is the forty-millionth part of the meridian, and the actual meter made of platinum are identical is of no consequence.</Callout> The modern meter bars are constructed by the Inter- national Metric Bureau, an institution established by the civilized nations of the world, who all contribute toward its maintenance. <Callout type="tip" title="Pro Technique">The only necessary linear units are the kilometer, the meter and the millimeter for long measure.</Callout> For capacity measures the liter and the milliliter are sufficient, and for weights, the kilogram, the gram and the milligram. 236 A CORRESPONDENCE COURSE IN PHARMACY It is not only unnecessary but burdensome to use so many different units. The superfluity of these many units is well exemplified by the following illustration : In America the monetary unit is called the dollar. In common speech we speak of ten dollars as an eagle, of the tenth of a dollar as a dime, the one-hundredth part of a dollar as a cent, and the one-thousandth part of the dollar as a mill. But no sensible person would count money in eagles, dollars, dime's, cents and mills. We find the dollar and the cent amply sufficient for all purposes. In the metric system the only necessary linear units are the kilometer, the meter and the millimeter. For capacity measures the liter and the milliliter are sufficient, and for weights, the kilogram, the gram and the milligram.
<Callout type="risk" title="Risk of Injury">The length of the seconds pendulum is hardly ever mentioned in connection with the metric system any longer, and the length of the meridian has now but a theoretical and sentimental connection with the metric system based upon the meter.</Callout>
237 A CORRESPONDENCE COURSE IN PHARMACY The following tables of the weights and measures of the metric system are sufficient for purposes of study: Linear Measure 1 kilometer = 1,000 meters 1 hektometer = 100 meters 1 dekameter = 10 meters 1 meter = 1 meter 1 decimeter = 0.1 meter 1 centimeter = 0.01 meter 1 millimeter = 0.001 meter 1 meter is equal to 39.37 inches, and 25 millimeters nearly equal inch. Square Measure 1 square kilometer = 1,000,000 square meters 1 square meter = 100 square decimeters 1 square meter = 10,000 square centimeters 1 square meter = 1,000,000 square millimeters Land Measure 1 square meter is called a centiare 100 square meters is an are 10,000 square meters is a hektare. Cubic Measure 1 cubic meter = 1,000 cubic decimeters 1 cubic decimeter = 1 ,000 cubic centimeters The cubic meter is called a Stere. Capacity Measures 1 kiloliter = 1,000 liters 1 hektoliter = 100 liters 1 dekaliter = 10 liters 1 liter = 1 cubic decimeter 1 deciliter = 0.1 liter 1 centiliter = 0.01 liter 1 milliliter 0.001 liter One liter is equivalent to about 33.8 U. S. fluid ounces. Weight Units 1 kilogram = 1,000 grams 1 hektogram = 100 grams 1 dekagram = 10 grams 1 gram = 1 gram 1 decigram = 0.1 gram 1 centigram = 0.01 gram 1 milligram = 0.001 gram One gram is equivalent to 15.432 grains (nearly).
Key Takeaways
- The metric system was designed as a decimal-based system for simplicity.
- The gram is the unit of weight in the metric system, derived from the mass of water at 4°C.
- The modern metric system uses standardized units like meters, grams, and liters.
Practical Tips
- Use the kilometer, meter, and millimeter for linear measurements to avoid redundancy.
- Employ the liter and milliliter for capacity measures, and the gram and milligram for weights.
- Understand that the metric system is based on decimal values, making it easier to calculate.
Warnings & Risks
- Be cautious of the historical context; some units like the seconds pendulum are no longer relevant.
- Do not rely solely on theoretical standards when practical measurements can be used.
- Avoid confusion with obsolete or redundant units in the metric system.
Modern Application
While the core principles of the metric system remain valuable for modern survival preparedness, it's important to adapt and integrate these concepts with contemporary tools and practices. Understanding the metric system is crucial for accurate dosing and measurements in emergency situations, ensuring that critical resources are used effectively.
Frequently Asked Questions
Q: What is the basis of the gram as a unit of weight in the metric system?
The gram is based on the mass of a cubic centimeter of water at 4°C. This was chosen because it provides a consistent and easily reproducible standard for measuring weight.
Q: Why are some units like the seconds pendulum no longer mentioned in modern metric systems?
The seconds pendulum, which was used as a reference point for defining certain metric units, is now considered outdated. Modern standards rely on more precise and universally accepted methods.
Q: How does the metric system simplify weight and volume measurements compared to older systems?
The metric system simplifies these measurements by using decimal values, making it easier to convert between units without complex fractions or ratios. This is particularly useful in emergency situations where quick calculations are necessary.